Season Preview: Julian Vaugn and Jerrelle Benimon

There was a constant clamoring heard over the off-season, several variations on a theme:

". . . but if the Hoyas hope to return to the top of the Big East, they will need to do a better job on the boards."

Julian Vaughn will have to be a strong rebounder and hang on to the ball to get major minutes this year.

Jerelle Benimon can earn some minutes if he can play strong defense and grab some rebounds.

Let's take a look at each of these statements (I only made two of them up), one at a time.


Measuring Rebounding and It's Importance

Rebounding has been a topic of great concern here, and all over Hoya nation. But before I jump headlong into the charts and tables, I thought I'd review some of the basics we've covered here.

When we discuss rebounding, we like to talk about rebounding percentages, rather than raw rebounding totals or the slighly more sophisticated rebounding margin (tot. rebounds - opp. tot. rebounds).

Why? Let me re-post a brief explanation Alan provided last season:

The most commonly used measure of rebounding is rebounding margin. There's a number of problems with this:

• Rebounding margin mixes offensive and defensive rebounding. Rebounding margin nets offensive and defensive rebounds for both teams, but the problem is that offensive and defensive rebounding are related, but different skill sets. Good offensive rebounding tends to be the result of strong individual effort. Defensive rebounding is much more of a team effort because it is much more highly dependent on all players establishing proper position. Good offensive rebounders often rely more on athleticism; defensive rebounders on position. More importantly, players rebounding on defense have positional advantage -- and rebounding margin doesn't account for that.

• Rebounding margin fails to compensate for differences in opportunity. There's an opportunity for a rebound on every missed shot. But not every possession ends on a missed shot. Some end on a made shot; some on a turnover. Since a team is more likely to get a defensive rebound than an offensive one, rebounding margin can make a team appear worse or better than it is simply because a team has more offensive opportunities than defensive or vice versa. For example, a team that forces a ton of turnovers will have less defensive rebounding opportunities and a lower rebounding margin than you'd expect. (Georgetown under Thompson would actually have an inflated rebounding margin over the years -- a negative turnover margin and better shooting than opponents means many more defensive rebounding opportunities).

• Rebounding margin fails to account for pace. More possessions means more opportunities for rebounds. This will not make a good rebounding team look poor, but a faster pace will make a good rebounding team look even better under rebounding margin.

A much better statistic is rebounding percentage. It is simply the number of rebounds a team gathers divided by their opportunities to grab a rebound. It is split into offensive and defensive rebounding percentage so as to avoid the problems of rebounding margin.

Last season, Georgetown's defensive efficiency slumped in conference, as the team finished the Big East regular season allowing 1.03 points per possession, the most since 2004-5. This was often attributed to poor defensive rebounding, allowing many second-chance points (think Pitt or St. John's).

Here are the team's defensive efficiencies and defensive rebounding percentages for the past five seasons:

Year        D.Eff.   Rank       DReb%    Rank
2004-5      105.2     8*        62.9       6*
2005-6      101.9     6         67.2       3
2006-7       97.3     4         63.1      13
2007-8       92.4     2         66.8     t-6
2008-9      103.1     7         63.2      12

*There were 12 teams in the Big East in 2004-5, 16 teams in the following seasons; all data from StatSheet.com

The Hoyas have only been among the league leaders in defensive rebounding once in the past five seasons, and that year (2005-6) was not a particularly strong defensive year. Indeed, while the team struggled to rebound defensively in 2006-7, the defense as a whole showed a strong improvement over the previous season, and the outstanding defensive team the next season were only middling defensive rebounders.

Of course, rebounding doesn't exist in a vacuum but is a component of overall team play. In fact, it is one component of what we call the Four Factors, first named and described by Dean Oliver. Oliver hit open the concept when he realized that each possession will end one of four ways (here from the defensive perspective):

• a made field goal (opp. eFG%)
• a missed shot rebounded by the defense (D. Reb. %)
• a turnover (opp. TO Rate)
• a foul resulting in free throws (FT Rate)

If you account for these four factors when looking at a box score or season recap, you'll have a fairly good idea of what went well and what did not. Moreover, since rebounding is only a component of total team defense, some context must be considered when looking at rebounding percentages.

For example, Syracuse is normally a mediocre to poor defensive rebounding team, averaging 63.5% Def. Reb. over the past five seasons while playing above-average defense in four of those five years. Of course, Jim Boeheim's squads primarily play a zone defense, which eschews strong defensive rebounding for low shooting percentages allowed and few fouls committed.


Let's return to the table above, but fill in all four of the factors for each season:

Year      D.Eff.  Rank     DeFG%  Rank    DTO%  Rank    DReb%  Rank    FTRate Rank
2004-5    105.2     8      48.5     8     20.4    6     62.9     6      37.5    8
2005-6    101.9     6      48.9     9     19.3    7     67.2     3      26.4    4
2006-7     97.3     4      45.2     3     20.9    8     63.1    13      28.1    1
2007-8     92.4     2      41.8     1     20.3    7     66.8   t-6      39.8   12
2008-9    103.1     7      49.2   t-8     21.0    5     63.2    12      37.1   11

All data from StatSheet.com

Hopefully the first thing that jumps out is that the biggest driver of defensive efficiency is opponent's eFG% - if the other team isn't making shots, they're going to have a hard time scoring.

But we're here to talking about rebounding, so let's take a look at each season:

• 2004-5: The team was pedestrian across the board (remember, this was the old, 12-team Big East, so a ranking of 6 is just average). The one thing I did notice was that the league average defensive rebounding rate was only 63.2%, which seems especially low. Perhaps most of the teams in the old league favored zone?
• 2005-6: The Hoyas had an odd combination of strong defensive rebounding (a man-to-man trait) and few fouls committed (a zone trait). Along with the the poor shooting defense and few turnovers forced, this looks like a tall but defensively passive team (likely due to the short bench). Here, the strong rebounding was undoubtedly important - there is a substantial improvement defensively despite worse shooting defense and few turnovers forced.
• 2006-7: Georgetown's profile is very different here, much more like the zone-defense team that we discussed earlier. This team rebounded just as poorly as last year's club, but were able to ride their famous offense and an under-rated defense to the Final Four. This season shows clearly that, if a team defends shots well along with one other factor (here, committing very few fouls), that team can play stout defense - even if they give up a lot of second shots.
• 2007-8: And here, the lesson is simple - defend shooters better than any else has in the past five years, and everything else will just take care of itself. Obviously the Hoyas improved on the defensive glass, but that ridiculous shooting defense was the real story [UConn has the 2nd - 5th spots in def. eFG% over the past five years]. Indeed, in the infamous Davidson game, it wasn't the rebounding that failed the team, but a lack of turnovers and a complete inability to defend 2-pt FGs that doomed Georgetown in the second half. The pattern here - good rebounding, lots of fouls - smacks of a team playing mostly half-court man-to-man, and looks to have been a sharp change from 2006-7.
• 2008-9: Boy, the wheels sure came off that sucker. One reason I made sure to add rank next to each column is because the Big East's overall offensive (or defensive) efficiency varies from year-to-year: 2008-9 was the highest scoring in the past five seasons, at 1.041 points per possession, after 1.027 ppp the previous year. So despite the large uptick in def. efficiency, the Hoyas were actually better than average (or median) defensively in conference. The increase in forced turnovers and still high fouls indicates a bit more pressing by the defense, but the poor shooting defense was too big a handicap to overcome. If we compare last year to 2005-6 and call the differences in TO Rate and FT Rate a wash, the poor defensive rebounding last year looks to have cost the Hoyas about 1 point of defensive efficiency.
  

Is 1 point of defensive efficiency significant, especially when the typical spread in the conference is about 20 points? Well, it certainly could be when a team is seemingly winning most lopsided games but losing most close ones, and the Hoyas did in conference last season.

Returning to a previous post on luck (as defined by the difference between actual and expected wins), we can actually just plug in that 1 point less defensive efficiency (about 0.6 points per game) and see what it's worth: ~0.4 wins. Not as much as you may have expected - if you want to round up and just call it one more win in conference play, would that have been enough to get the Hoyas on (or even over the bubble)? I'll leave that conjecture for others.


A quick bit on offensive rebounding

Throughout the discussion above, I've been entirely concerned with defensive rebounding. As Alan noted in the section I co-opted from him, offensive and defensive rebounding rates don't necessarily correlate, since they depend upon complementary, not identical, skills and in part on the head coach's game strategy.

How have the Hoyas rebounded offensively the past five seasons?

Year        DReb%    Rank     OReb%   Rank     TReb%   Rank
2004-5      62.9       6       33.5     9       48.2     9
2005-6      67.2       3       38.1     4       52.7     4
2006-7      63.1      13       41.3     2       52.2     4
2007-8      66.8     t-6       31.7    12       49.3    12
2008-9      63.2      12       33.7    12       48.5  t-13

all data from StatSheet.com

Georgetown's best offensive rebounding season (2006-7) was also one of their worst for defensive rebounding. More to the point, despite losing 7'2" Roy Hibbert, 6' 9" Vernon Macklin and 6' 8" Patrick Ewing Jr., last season's team - while no great shakes - actually was a better offensive rebounding club that the 2007-8 team.

I've also included total rebounding percentage [= (OReb% + DReb%)/2] in the table, and this final stat likely jibes better with common perception. Georgetown was not historically bad in either offensive or defensive rebounding last season, but by performing poorly in both the team's total rebounding rate ranked as low as any JTIII-team.

I do wonder though, if the two strong rebounding seasons (Hibbert's sophomore and junior years) may eventually prove the aberration for the 21st-century Hoyas.



Julian Vaughn will be asked to shore up the Hoyas' meager rebounding this season. To understand whether he can help, we'll need to ask how well has Vaughn rebounded in the past, who will he replace, and can we expect an improvement season-over-season.

How well has Julian Vaughn rebounded his first two seasons?

Year       %Min      OReb%      DReb%
Frosh      29.6      10.8       10.2
Soph       21.5      11.1       10.2

I don't have access to conf. only stats for Julian his freshman year at Florida St., so I'll be using full season stats in this section.

Okay, we have some numbers, but can we give them some context? Thankfully, Ken Pomeroy has provided us with a very handy chart, showing average rebounding percentage as a function of height for all college players (click on any figure to enlarge):

Julian Vaughn's height is listed as 6'9" by Georgetown (he was listed at 6'10" at Florida St. [.pdf], so either he is shrinking or the Seminoles may be cooking the books). For the average 6'9" Div. I player, we'd expect an OReb% = 9.3 and a DReb% = 16.5.

From the chart, Vaughn is an above average offensive rebounder, but a suprisingly below-par defensive rebounder. In fact, in each of his first two campaigns, Vaughn was more likely to get an offensive rebound than a defensive one.


Who will Vaughn be replacing?

The primary additional minutes Vaughn will get this year were used by DaJuan Summers last season. To put this bluntly, those minutes will not be hard to replace, at least from a rebounding perspective. Summers' number last season (OReb% = 5.5, DReb% = 11.7) were underwhelming, both as the nominal power forward for the Hoyas, and as a 6'8" college player.

Vaughn looks to have the skill set to greatly improve Georgetown's offensive rebounding this year, but probably won't be able to help much on the defensive glass outside of Greg Monroe (OReb% = 9.0, DReb% = 16.6).

When Vaughn isn't on the floor this year, he'll likely be subbed for by Henry Sims (OReb% = 7.0, DReb% = 12.7), who represents an incremental upgrade from Summers, but not much more.


Will Vaughn be a better rebounder this year?

This seems to be the most intuitive step that I've not addressed - as players get older and stronger, they should be able to out-compete younger players for rebounds, and therefore we'd expect a returning player (e.g. Julian Vaughn) to likely be a better rebounder this year.

That assumption is easy enough to check. Below I've plotted year-over-year defensive and offensive rebounding stats for Big East players from 2005-2008:

A quick explanation

• The x-axis is a player's rebounding rate for a given season, while the y-axis is that player's rebounding rate the following season.
• The markers are sized by player's % minutes played (>10% minutes both years to qualify) and colored by player height.
• The black line is a linear fit to the data, weighted by player minutes.
• The gray lines are the 95% prediction bands - 95% of the markers should be within these lines.
• The blue line is the 1:1 line - players that fall along the line performed at the same level both seasons.

The takeaways here are several: the fitted line of defensive rebounding is above the 1:1 line up to about 16%, indicating that defensive rebounders tend to improve year-over-year up to about this point. But the difference from year-to-year is very small, certainly less than 1% change on average. For offensive rebounding, the fitted is below the 1:1 line above about 5%, which implies that those players who are strong offensive rebounders (>5%) do not, in fact, improve from one year to the next. Most importantly, the majority of the data is well-scattered about the 1:1 line, especially defensive rebounding. Therefore, most of the change from one year to the next is just statistical noise, and that players, on average, rebound at the same level each season. That is, rebounding ability (or desire) is fully formed when the players arrive in the Big East from high school.

So the results are mixed for Julian Vaughn. Statistically, if there's any change we'd expect a small improvement in defensive rebounding and a small decline in offensive rebounding.

More likely, what we've previously seen from Vaughn (and Sims) just may be what we can hope for during this season.



Can Jerrelle Benimon help?

A complete unknown coming into this season is Jerrelle Benimon, a player few are expecting to contribute significant minutes this year. Could Benimon be some sort of stealth rebounding freak? Possibly, but we have no way of knowing right now, and no mention of such prowess was made during Kenner League.

What we do know is that he is 6'7" and 242 lbs. From Ken Pomeroy's chart above, we can see that 6' 7" players are part of the upper plateau for defensive rebounding, on average garnering 15.3% of defensive rebounds. So Benimon certainly has the right body-type for rebounding.

But, as we saw near the top, defensive rebounding can be an overvalued stat for overall team defense, and I'd like to see his full skill set before I suggest he should be taking minutes from Vaughn or Sims.

Expected Rebounding by Height

A few years ago, Ken Pomeroy put together a chart of the average rebounding percentages by height.

Using that information, here's how our players stack up:

Player     Hgt      Exp DR%     Act DR%        Exp OR%     Act OR%
Monroe     6-11      17.4        13.7           10.4         6.5
Sims       6-10      16.5         7.0            9.2         4.7
Vaughn     6-9       16.5         5.7            9.3         9.2
Summers    6-8       16.1         9.3            9.1         4.9
Wattad     6-5       12.3        10.9            6.0         4.5
Freeman    6-4       11.6        12.7            4.8         5.6
Sapp       6-3       10.1        12.1            3.7         5.6
Clark      6-2        9.6         9.9            3.0         5.4
Wright     6-1        8.9         9.3            2.7         1.2 

Editor's note: I've updated the stats through the Pitt game, and only for KenPom's Top 150 teams - all games except Savannah St. and FIU. Individual and team splits on the right side bar will be updated after tonight's game.

Couple of notes on this:

1. This is before the Pittsburgh game.

2. The expected values are versus the players' heights, not positions.

3. Defensive rebounding tends to be much more of a team activity. Those numbers are harder to parse individually.

That all said, it seems pretty clear who is rebounding and who isn't, doesn't it?

Another post on rebounding

Georgetown lost to the Pitt Panthers yesterday, for the Hoyas' second loss of the season, due in large part to a massive discrepancy in rebounds: 48 to 23. That's a rebounding margin of -25, or two more than the total number of rebounds that the Hoyas secured.

A few weeks ago, SFHoya99 wrote a prescient article explaining a pair of slightly more sophisticated statistics (Off. Reb. % and Def. Reb. %), which we tend to use around here rather than rebounding margin. I won't explain here why we prefer them (do read his article if you'd like to know why, it's very good), but I will re-post the equations to calculate each.

.                      Off. Reb.
Off. Reb. % = ----------------------------
.             (Off. Reb. + Opp. Def. Reb.)


.                       Def. Reb.
Def. Reb. % = ----------------------------
.             (Def. Reb. + Opp. Off. Reb.)

These are simple calculations - we're just looking at the number of rebounds gathered divided by total opportunities to get those rebounds. We'd expect teams to get about 1/3 of their own misses and 2/3 of their opponents', and we treat offensive and defensive rebounds separately. Again, re-read the above linked article for more information.


About a year ago, I also wrote a note about Georgetown rebounding difficulties, added to the end of a recap of an ugly road win against Rutgers. I'd like to return to it, and update the underlying statistics in an attempt to put the Pitt game into some perspective.

I mentioned then, and again in yesterday's recap, another rebounding stat called Total Reb. %. This is also a simple-to-calculate metric that serves as the stat-head analogue to rebounding margin, and is merely the average of Off. Reb. % and Def. Reb. %. That is:

.             (Off. Reb. % + Def. Reb. %)
Tot. Reb. % = ---------------------------
.                          2

If two teams perform equally well in a game at rebounding, each should end up with a Tot. Reb. % = 50%. Here's an example you might find in a typical box score:

Team A         vs.   Team B
OR   DR   TR         OR   DR   TR
14   20   34         10   28   38

If you were to simply look at rebounding margin, you'd say that Team B out-rebounded Team A by four. However, if you were to calculate rebounding percentages, you'd see that the teams were even on the glass. For example, Team A's OR % = 14 / (14 + 28) = 33.3; that is, while Team A was on offense there were 42 (= 14 + 28) rebounding opportunities, and they got 14 of them, or one-third. Here are all the numbers for our hypothetical game:

.     Team A          vs.        Team B
OR %   DR %   TR %         OR %   DR %   TR %
33.3   66.7    50          33.3   66.7    50

Of course, this is not to say that rebounding margin always gives misleading information. In yesterday's game, Georgetown ended up with a Tot. Reb. % = 32.2, which looks nearly as bad as the -25 rebounding margin I mentioned at the top.

After all this introduction, allow me to roll out another in a never-ending series of overly busy plots, looking at Georgetown's Tot. Reb. % for this and the last two seasons (click to enlarge).

The points represent individual games, the solid black line indicates the 50% rebounding rate (a draw with the opponent), the solid blue, red and gray lines represent moving averages of the data (n=5 for 2006-7 and 2007-8; n=3 for 2008-9) and the dashed lines are linear fits to each year's data.

A few comments and observations:

• Tot. Reb. % is not a stat that is adjusted for opponent, so playing a run of great or lousy rebounding teams can make your team look better or worse than they may be over the course of the season. For the sake of argument, we'll assume that the relative rebounding ability of teams played at the same time of year is roughly equal season to season.
  

• The three-year trend from comparing the linear-fit lines from each season indicates that this team is the worst of the three, and by a substantial margin. Do keep in mind that there is quite a bit of uncertainty for these fits which I don't indicate, so the differences would not be considered significant in the true sense of that word.

• More interestingly (to me) are the observed seasonal trends from comparing the moving averages for previous years, and which may be repeating again this year:
  1. After starting the season essentially neutral or noisy, the team rebounding improves strongly in December. I suspect this is from a diet of "cupcakes" during the exam period.
  2. The Big East conference season begins, and it is a shock to the Hoyas. Rebounding performance drops dramatically.
  3. By February, the team has recovered - or more likely worked hard in practice - and is rebounding nearly as well as during the December stretch.
  4. By March, the rest of the league has caught up, and Georgetown is now rebounding equally well as their opponents.

• Just by looking at the moving averages, this year's team, while starting much more poorly than previously, looks to have recovered to roughly last year's level, before the beating from Pitt. However, it should be pointed out that about this time last year, the Hoyas took the same type of pounding on the boards in the aforementioned Rutgers game.

The question to be answered in the next few weeks is whether this team can follow the lead of its predecessors and make the same type of commitment to rebounding by February.

The Problem of Rebounding

There's understandably a lot of teeth-gnashing about the Hoyas' rebounding this year. It's been abysmal, or at least it seems that way to most people watching, including myself.

In addition, there's a perception that Thompson's teams have never rebounded well. A perception that the offense cripples rebounding; that Thompson's choice of personnel has left the team lacking in the ability to grab boards.

Has Georgetown under Thompson really been that poor at rebounding? What are the possible reasons why this would be true? Is it the result of personnel choices or strategic choices or both? If the team has rebounded well at some time, what was different?


How do you measure rebounding?

The most commonly used measure of rebounding is rebounding margin. There's a number of problems with this:

• Rebounding margin mixes offensive and defensive rebounding. Rebounding margin nets offensive and defensive rebounds for both teams, but the problem is that offensive and defensive rebounding are related, but different skill sets. Good offensive rebounding tends to be the result of strong individual effort. Defensive rebounding is much more of a team effort because it is much more highly dependent on all players establishing proper position. Good offensive rebounders often rely more on athleticism; defensive rebounders on position. More importantly, players rebounding on defense have positional advantage -- and rebounding margin doesn't account for that.

• Rebounding margin fails to compensate for differences in opportunity. There's an opportunity for a rebound on every missed shot. But not every possession ends on a missed shot. Some end on a made shot; some on a turnover. Since a team is more likely to get a defensive rebound than an offensive one, rebounding margin can make a team appear worse or better than it is simply because a team has more offensive opportunities than defensive or vice versa. For example, a team that forces a ton of turnovers will have less defensive rebounding opportunities and a lower rebounding margin than you'd expect. (Georgetown under Thompson would actually have an inflated rebounding margin over the years -- a negative turnover margin and better shooting than opponents means many more defensive rebounding opportunities).

• Rebounding margin fails to account for pace. More possessions means more opportunities for rebounds. This will not make a good rebounding team look poor, but a faster pace will make a good rebounding team look even better under rebounding margin.

A much better statistic is rebounding percentage. It is simply the number of rebounds a team gathers divided by their opportunities to grab a rebound. It is split into offensive and defensive rebounding percentage so as to avoid the problems of rebounding margin. All the rebounding percentages here will be from www.kenpom.com unless otherwise noted.


What is a good rebounding percentage? Poor? Average?

In 2007-2008, the average offensive rebounding % -- the % of shots the offense got an offensive rebound on -- was about 33%. The best offensive rebounding team in the nation was North Carolina at over 42%; the worst was Air Force at 20%.

About 70 teams (of 341) were under 30%. Only about 60 were over 36%. So 210 of the 341 teams -- about 2/3 -- were within 3% either way of average.



For defensive rebounding, obviously the average is the reverse -- 67% is about the average. The best defensive rebounding team last year was Utah at 75%. Only two teams were at 60% or lower -- Maryland Eastern Shore and Kennessaw State. Just like offensive rebounding, 2/3 of the teams were between grabbing 64% and 70% of defensive opportunities. (Note: Pomeroy's stats state defensive rebounding % as opponents' offensive rebounding %. I've just flipped the numbers.)



Think about those for a second. On average, 1 in 3 rebounds are grabbed by the offense. How often is the scream "Box out!" heard at the first offensive rebound allowed? Most fans treat defensive rebounding like a save opportunity -- something that should be converted at 100%. It's simply not going to happen.

The rebounding percentages Ken Pomeroy calculates aren't adjusted for competition. So while we'd obviously expect Georgetown to be well above average in terms of all 341 DI teams, we're also facing a Big East schedule that most of those teams aren't playing.


So, has Georgetown really been that bad? Have they always been that bad?

This year, they're pretty bad.

More of the focus from fans has been on the defensive rebounding. Before the Tennessee game, the Hoyas were only grabbing 63% of defensive rebounds -- ranking 264th in the nation. The Tennessee game didn't help -- they only grabbed 56% of all possible defensive rebounds.

What's the difference between 60% and an average 67%? Let's say there are about 45 opportunities for a defensive rebound for the Hoyas in a game. That's actually been high for this season -- but even with 45 opportunities, the 7% difference there is about three rebounds a game.

Of course, we expect them to be better than average, but improvement here is likely around five points per game. That's huge over the course of the season, but it isn't the only reason we lost to Tennessee.

Just as disturbing is the offensive rebounding. Before the Tennessee game, the Hoyas were only grabbing 25% of our possible offensive rebounds, ranking 316th. The Tennessee game was an improvement at 30%, but still awful. Our previous season low was seven and half percentage points higher. A great offensive rebounding team would be 15% points higher.

So Georgetown is not a good rebounding team. But have the Hoyas always been that bad?

Year	O Reb %	O Reb Rank	D Reb %	D Reb Rank
2005	34%	92	65%	287
2006	35%	70	71%	38
2007	40%	8	66%	191
2008	34%	132	67%	157

Some interesting notes:

• The Hoyas haven't been a bad rebounding team under Thompson. Georgetown has been an average rebounding team overall during Thompson's tenure. Only two years have they been below average on either stat (of eight) -- in defensive rebounding in Thompson's first year and just slightly in defensive rebounding in the Final Four year.
• They've been a good -- or great -- rebounding team twice. Offensive rebounding during the Final Four run was fantastic, and defensive rebounding the prior year was very good as well.

What has caused the mediocre defensive rebounding?

Well, one thing that hasn't caused it is the offensive system. It's amazing to me that people blame the mediocre defensive rebounding on the offense, but they do.

But several defensive choices could have caused it. And number one on the list has to be the usage of zone defense.

It is no secret that conventional wisdom states it is much harder to defensive rebound out of a zone. A player isn't guarding an individual player so it is simply harder to body up.

How much teams pay man to man and play zone is not publicly available information, so there was no systematic way to verify this or quantify this. But we can look at Syracuse.

Syracuse played the 2-3 almost exclusively over the past five years (and longer). From 2004-2008, which is the five years where we have complete rebounding numbers from Pomeroy, they have had a slew of quality rebounding personnel -- Craig Forth, Hakim Warrick, Paul Harris and Arinze Onuaku.

That has been reflected in their offensive rebounding percentage -- 38% over that time period. That ranked an average of 33rd in all of college basketball, despite playing conference games against NBA frontlines.

On the other hand, their defensive rebounding % was just 65% and ranked 240th. That's 200 teams of ranking difference and 8% difference from average.

The simplest explanation why is that they have played almost exclusively zone.

Unlike his father, Thompson has shown a willingness to play zone. More importantly, the Hoyas tend to play zone when they have a thin frontline -- when personnel already are weaker on rebounding. It is a way to protect big men from foul trouble, but it is not helping the rebounding.

There are other systematic choices that hurt rebounding.

One is releasing your guards and forwards on the fast break. This may be exacerbating the issue this year (Freeman has a ton of fast break points but not so many defensive rebounds), but was hardly an issue in prior years.

Another is the decision to funnel drivers to the shot blocker. By challenging shots, the shot blocker is commonly out of position for the rebound. This enhances our FG% against but hurts on the back end. The other guards and forwards need to do a better job of rebounding if Monroe is going to continue to help. But overall, given how good our defenses have been, isn't this a trade off proven to be worth making?

What about personnel? There's no doubt Thompson likes to play players "down" a position. This is his fifth year, and for most of his time here, he's had a small forward playing power forward (Bowman and Summers) and a weaker rebounding player at SF (Owens, then Freeman).

What effect has it really had? Our defensive rebounding when Green was the center with Hibbert his only backup was awful, but the next year Thompson had his best rebounding team of his tenure at Georgetown.

Hibbert was still only playing 60% of the minutes, and Jeff was playing 80%, which means that only 40% of the time did we actually play them together and even less of the time did we have Bowman at the three for a truly strong rebounding team.

With Hibbert, Green and Bowman, we had three strong defensive rebounders.

The next year, with Summers replacing Bowman, the rebounding dropped off, and almost all the difference was in that Summers was awful where Bowman was a strong rebounder even from the three.

Was there something else going on, defensive scheme-wise, that made Bowman a better rebounder than Summers? Perhaps. But there's also a good chance that Bowman was simply a senior and Summers a freshman.

More importantly, Thompson has had a strong defensive rebounding team when he's had a rotation of enough strong rebounders to always have two of them on the floor at the same time.

When he wasn't had that, the rebounding hasn't been nearly as strong.


What about offensive rebounding?

In his first four years at Georgetown, Thompson's teams have average a ranking of 75th in the country in offensive rebounding. In 2005, with Bowman playing PF, the team ranked 92nd. Last year, with Summers at PF, the team ranked 132nd. Again, these numbers aren't adjusted for competition, so ranking in the Top 1/3 of basketball isn't bad.

And in 2007, Georgetown ranked eighth. Yes, they had an NBA frontline in Hibbert and Green. Roy in particular was an excellent offensive rebounder. But still, to grab 40% of our team's misses while playing teams like Pitt and Connecticut is fairly incredible, and it was an unsung driver of the team's amazingly efficient offense that year.

The team is not grabbing any offensive rebounds this year. Why not? It's most likely a combination of small sample sizes and a young frontcourt. More important is what is not driving it: the offensive system.

The traditional Princeton offense has usually involved abandoning offensive rebounds in exchange for getting back on defense. Since the teams that run it have historically been disadvantaged in speed and overall talent, that trade-off has made a lot of sense.

Thompson has never run a traditional Princeton, though. Not at Princeton; not at Georgetown. And at Georgetown, he hasn't given up on getting offensive rebounds.

The system, despite often placing big men on the perimeter, has not significantly hindered our offensive rebounding. Why would it start now?

If this drop in offensive rebounding is not just a small sample, it would seem to be personnel driven in two ways. Summers, though improving last year in his defensive rebounding, has never been a good offensive rebounder. Monroe so far has not been as good a rebounder as Roy. Though I suspect that will change.

The second way is in how the team's personnel scores. Offensive rebounds seem to often occur after help defense down low. If the Hoyas low post scoring and drives to the basket do not create those situations, the offensive rebounding will suffer.


The Future

Unfortunately, the future is somewhat bleak for rebounding. Rebounding woes seem to be personnel-driven. The team has successfully rebounded both offensively and defensively in the past, but when it has done so, it has done so when it has had a strong rotation of quality rebounders. The players needn't have been all traditional big men, but there needs to be at least enough quality rebounders to always have two of them on the floor at the same time.

Right now, the Hoyas only have one player who might be strong (Monroe) and a player who has played
the third player in a rotation (Summers). Monroe will likely develop into a quality rebounder by year's end, but the key seems to be if Vaughn or Sims can become a strong enough rebounder to play well when Monroe and Summers are out, and if they can become a strong enough defender and offensive player that the Hoyas can play less zone to protect Monroe.

It may not get any better the next couple of years. While Sims may develop into a strong rebounder, Summers and Monroe are not locks to return next year. With DaShonte Riley decommitting, that means Georgetown may go into next year with a possibly strong Henry Sims and Julian Vaughn, who was not a strong rebounder at Florida State. Even the year after, when Summers and Monroe are all but guaranteed to be gone, the only big man recruit is Nate Lubick, who will be a freshman.

The Hoyas may fill in some of the gaps with recruits who can come in and rebound right away. But if Summers and Monroe jump, get used to screaming "Box Out!"

Analysis: Georgetown 58, Rutgers 46

Workmanlike, or perhaps desultory.

Both would seem to accurately describe Georgetown's 12 point win at the RAC this afternoon in Piscataway against struggling Rutgers. It certainly is an indicator of how far Georgetown has come in the last 3 1/2 years that a 12 point road win in conference can leave one disappointed, but the Hoyas have raised the bar and fans are happy to oblige.

Behind 11-23 3FG shooting, Georgetown closed the 1st half on a 10-2 run, then opened the 2nd half 14-5 to turn a 1-point deficit into a 16-point lead. Let's run the numbers:

	Offense				Defense
	1st Half	2nd Half	Total		1st Half	2nd Half	Total
Pace	29	29	58
Eff.	94.7	106.1	100.5		70.2	89.0	79.7
eFG%	58.7%	63.2%	60.7%		33.3%	35.5%	34.4%
TO%	21.1%	24.0%	22.5%		31.6%	20.5%	26.0%
OR%	8.3%	23.1%	16.0%		47.6%	52.2%	50.0%
FTA/FGA	0.0%	68.4%	31.0%		0.0%	29.0%	14.8%
FTM/FGA	0.0%	36.8%	16.7%		0.0%	12.9%	6.6%
Assist Rate	54.5%	44.4%	50.0%		55.6%	50.0%	52.6%
Block Rate	8.3%	14.3%	10.5%		13.0%	11.5%	12.2%
Steal Rate	7.0%	17.1%	12.1%		14.0%	13.7%	13.9%
2FG%	50.0%	42.9%	47.4%		30.4%	30.8%	30.6%
3FG%	45.5%	50.0%	47.8%		28.6%	40.0%	33.3%
FT%	-	53.8%	53.8%		-	44.4%	44.4%

*Neither team shot a FT in the 1st half


The 1st half was the least efficient offensive 1st half for Georgetown this season (previously, that honor went to the Alabama game), thanks mostly to a poor showing on the offensive glass, where the Hoyas normally average an OReb percentage of 35%. Georgetown collected a total of 4 offensive rebounds on 25 opportunities.

While the offense improved in the 2nd half, the defense did worse. But, thanks mostly to the Scarlet Knights terrible shooting, the game was never in doubt. Rutgers came in with an eFG% = 44.2% (315/341 teams), so this was not a surprise, but the OR of 50%(!!) certainly was, especially as they came in as a middle-of-the-road offensive rebounding team (34.4%, 139/341). I suspect that Georgetown's recent struggles with rebounding may have encouraged Fred Hill to have his team crash the offensive glass, and frankly that was about all that went well for Rutgers today.

Today's highlight (courtesy of Jon Wallace):



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More on Rebounding

Today's game, along with the Memphis game, most prominently exposed a weakness of this Georgetown team, namely rebounding. I thought I'd take a further look at what tempo-free stats can tell us about rebounding performance.

First, allow me to introduce yet another stat to the canon, Total Rebounding %. This is simply the sum of OR% and DR%, divided by 2 (as I normally report opponent's OR%, DR% is the equivalent of [1- Opp OR%]). If 2 teams are equally adept at rebounding, you'd expect each to have Tot. Reb. = 50%, regardless of how many times each team missed a shot. And therefore, if your team has a Tot. Reb. > 50%, they did a better job than their opponent on the glass that game.

Here's a plot of both last year's and this year's Tot. Reb. %, both plotted against month and day.

That egregiously high data point from last season was the Seton Hall game, while the lowest point this season was today's game against Rutgers. Through the first eight games of this season, the rebounding effort was comparable to last season, but the Memphis, Fordham and now Rutgers games are all poorer than anything seen last year.

But comparing total rebounding % from game to game may be a bit too simplistic; after all, getting beat on the boards 60% to 40% by Memphis is one thing, but is it on a whole 'nother level when Fordham does it?

We can account for this by using KenPom.com's offensive and defensive factors stats to produce something analogous to my performance stats, but for rebounds. I can work out what we would expect each team to allow for total rebounding against Georgetown, and compare this to what Georgetown actually got. That is to say:

Tot. Reb. Performance = Total Reb. % / [(Ave. Tot. Reb. % + Opp. Ave. Tot. Reb. % Allowed)/2]

Here's the same plot as above, but now we're looking at Tot. Reb. Perf. rather than Total Reb. % (note that Tot. Reb. Perf. is also a percentage, where 100% would mean that your team rebounded as well as expected, higher = better, lower = worse).

While the two plots look similar, there are some subtle improvements. Now we can see that last season, Georgetown was normally quite strong on the glass and never rebounded less efficiently than 89% of expected. At Seton Hall, the Hoyas rebounded at 152% of expected efficiency, and, yes, that 89% was the Final Four game against Ohio St.

Meanwhile, the last 2 games this season have truly terrible (Fordham = 80%, Rutgers = 66%). For the Memphis game, Georgetown rebounded at 86% of expected efficiency, which is still poor but no where near as bad as today's effort; the 4th, and earliest, bad rebounding game was against ODU, where just about everything else went right.

As always, I must remind my reader(s) that the stats data I'm using for this year are subject to change as the season progresses - who knows, maybe Fordham and Rutgers will suddenly turn out to be great rebounding teams (I doubt it).

To sum up, if you are worried about how well the Hoyas have been rebounding the ball, you've got every right to be.