Sunday, April 19, 2009

Season Post-Mortem IV: More "Luck"

A couple of weeks ago, Tom took a look to see if part of the Hoyas' troubles were caused by "bad luck" due to abnormally high opponents' free throw shooting. He found that most of the Hoyas' bad luck came from playing good shooting teams.

Still, it was a good idea to look into "luck." Even at the end of the season, the Hoyas were still considered a good team by many of the statistical systems out there. That's because those systems look at full year points scored and points allowed. In most cases, those numbers predict actual winning percentage very well. When they don't, the system Pomeroy uses, for example, kicks the difference out to a factors he's unfortunately labelled "luck."

The prime driver of this statistic is performance in close games. (Blowouts can also play a role -- teams that blowout awful teams by more than other teams can be a bit overrated.) There's not doubt that actual random chance can play a role in close games. Think of how many times borderline calls have been made in a one point game, for example.

But there's also a whole lot of execution. Using "luck" to describe the fact that someone doesn't step on the end line in a blowout but does in a close game isn't quite right. Actual performance isn't so consistent as to attribute variances to chance; players play better sometimes and not as well other times. You can call that luck, and you may be right, but you certainly have to also leave open the possibility that college players can be affected by the situation.

In other words, did the Hoyas crumble down the stretch in tight games?

Subjectively, it certainly looked like it all year. How do the numbers back it up?

Year         Pomeroy Luck       Games Lucky/(Unlucky)
2005-06 -.035 -1.2
2006-07 .001 0.0
2007-08 .021 0.7
2008-09 -.113 -3.5


The Hoyas lost three to four more games than they should have based on their points scored and points allowed last year. That's an additional three to four losses on top of most of what plagued the team all year -- it's not how much the Hoyas scored allowed, it's when.

So what causes this?

One possibility is this is simply a consequence of the fact that Pomeroy calculates his ratings on a full year basis. If the team really did, in fact, collapse halfway through the season and in effect become a different team, then the early season Hoyas might be holding up the rating and the late season Hoyas might have just stunk instead of playing poorly in close games. We'll check that in a later post.

Another possible cause is youth. I've looked into that here and found that while you can't rule it out, there's not a lot of evidence saying that youth is a common driver of "bad luck," which is somewhat surprising.

Another possibility, though, is that it really just was bad luck. Some shots rimmed out, some fouls weren't called, some opponents' shots went in. If that's true, then that is good news for Hoya fans -- this team may just get a bit better by regressing to the mean in "luck" next year.

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