tag:blogger.com,1999:blog-8609450545815012880.post4527485938705363856..comments2023-10-26T02:21:09.121-06:00Comments on Hoya Prospectus: Analysis: It's the defense, stupidBrian Lernerhttp://www.blogger.com/profile/00844052204506883915noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-8609450545815012880.post-22845299149748343222007-12-24T23:43:00.000-07:002007-12-24T23:43:00.000-07:00Performance is calculated in "units" of points, so...<B><I>Performance</I></B> is calculated in "units" of points, so you are right, it isn't purely tempo-free. That is by intent. I guess I've spent too much time staring at Baseball Prospectus' obtuse stats (WXRL, WXL, Leverage), and wanted something readily tangible to any reader.<BR/><BR/>To get the stats the way you'd like, all I'd need to do is subtract predicted offensive efficiency from actual offensive efficiency for a game.<BR/><BR/>For example, based upon the stats through yesterday's games, if Georgetown played at Memphis tomorrow, you'd expect the Hoyas to have a game OEff of 94.7 (this is based upon GU's Adj. OEff and Memphis' Adj. DEff, along with a weighting factor for game location). In the actual game, they had a 101.7, which works out to a +7.0 OEff.<BR/><BR/>Well, I have a vague idea of what that means (points per 100 possessions), and you may too, but it's a bit abstract. You'd need to know what a good or bad OEff value is, and how important +7.0 in OEff is over the course of a typical game. But if I just multiply by actual game pace, we now know that the Hoyas scored +4.9 points more than expected, a number that just about anyone can understand.<BR/><BR/>So what would the effect be in comparing <B><I>performance</I></B> from games of different paces? For example, the game at ODU has an offense performance of +5.3 points, but in only 57 possessions. If you translate that to OEff, you'd get +9.3.<BR/><BR/>So, we can compare Memphis vs. ODU truly tempo-free, and get +7.0 vs. +9.3 pts/100 possessions, or using <B><I>performance</I></B> and get +4.9 vs. +5.3 points.<BR/><BR/>That difference may seem large to you, but if you look at the scatter in any of these performance stats over the course of a season, you'd see that the variability game-to-game mostly swamps this effect. <A HREF="http://hoyaprospectus.blogspot.com/2007/03/analysis-osu-performance.html" REL="nofollow">Here's the last look at <B><I>performance</I></B></A> I ran last season, as a preview for the OSU Final 4 game. The range in <B><I>performance</I></B> is -29 to +19 points, with a st. dev. of 11 points; the ranges and st. devs. are slightly less for offense or defense performance.<BR/><BR/>With regards to the offensive trend, the tempo-bias is nearly meaningless. Looking at a linear fits of the purported offensive trend (vs. date), the R^2 is 0.51 with <B><I>performance</I></B>, 0.50 with the tempo-free stat.<BR/><BR/>Having said all that, it is certainly trivial for me to transform <B><I>performance</I></B> stats into completely tempo-free values. Maybe I'll pursue it a bit further down the road (with last year's data?) and see how much change there is in the plots. But not tonight.Brian Lernerhttps://www.blogger.com/profile/00844052204506883915noreply@blogger.comtag:blogger.com,1999:blog-8609450545815012880.post-16360454982855205852007-12-24T14:10:00.000-07:002007-12-24T14:10:00.000-07:00Hmmm. I think you are correct in your conclusion,...Hmmm. I think you are correct in your conclusion, but your logic doesn't seem quite right to me. By looking at per game stats (rather than per possession stats) you are missing the major point of tempo-free stats, aren't you? So the overall upward offensive trend that you observed out of your analysis comes at least as much from our increased pace over the past 3 games (which is 12 possessions higher than the previous 5 games) than increased efficiency (which did increase 0.14 points per possession). So can you do the same analysis with expected points per possession rather than expected points per game? <BR/><BR/>I fully admit that I may be missing something here as I haven't spent a lot of time thinking about this. If I'm wrong, please feel free to let me know where I've misunderstood.Anonymousnoreply@blogger.com