Thursday, May 14, 2009

Means, Variances, and Coaching.

Malcolm Gladwell writes that basketball teams with inferior talent should run full court presses. The full court press is a high risk defensive strategy: it raises the likelihood that a defensive team gets a steal and an easy basket, but it also raised the likelihood that the opponent will get an easy basket. It is a higher variance strategy than a standard defensive strategy.

Such a strategy makes sense for a team with little talent. Such a team wants to raise the variance of outcomes, because it is the only way it can win. If an inferior team pursues a variance minimizing strategy, it will always lose, because its mean outcomes are lower than those of superior teams.

The worst coach I ever saw in any sport was the football coach for the Wisconsin Badgers before Barry Alvarez, a man named Don Morton. He was a horrible recruiter, so the team's talent was poor. He also ran a minimum variance strategy: three rushes in a row (around 2 yards per rush) and then a punt. During his time at Wisconsin, the Badgers won three Big Ten games in three years.

On the other hand, superior teams should attempt to minimize variance in the game. It is why I am not sure Brett Favre was a net plus to his teams over the past few years--he probably added too much variance. Mike Holmgren was a genius at reducing Favre's variance. I think had he stayed with the Packers, the two of them would have won a couple of more Super Bowls.

A study I would like to do at some point is a determination as to whether Walter Payton was more valuable than Barry Sanders. Sanders yards per carry average was much high than Payton's, but he surely gained the yards with a lot more variance. Someone needs to measure the two variances and run simulations. Perhaps after I retire.

The ideal back would get 3.5 yards per carry with no variance: such a back would guarantee scores and burn clock, giving the defense an opportunity to rest.


willie green said...

Hey, my brother thinks some of the same things I do. But wouldn't the ideal running back actually run 3.34 yards per carry?

Of course, I am all for a Brett Favre Study.

Anonymous said...

During their playing careers, there was a lot of debate on who was the better RB: Barry Sanders or Emmitt Smith? While Sanders had more spectacular runs, Smith was a more complete RB and had less of the variance you mentioned everytime he carried the ball. For instance, Sanders had lots of highlight reel runs but also a lot of rushes for losses which would put his offense in a bad position on the next down. By contrast, Smith was a more consistent RB who left his offense with a 2nd & 6 rather than a 2nd & 13.

Jonathan Weinstein said...

Sanders' average per play was always sensational compared to other running games -- but a bit subpar compared to passing games, which might be a more appropriate comparison given the high variance! His team didn't even think he was worth using in goal-line scenarios. I also always thought Emmitt was much more effective, although as always such comparisons in football are hard to separate from the team context.

Richard K. Green said...

I agree that Emmitt Smith may have been better than either, but because his teams were so much better, it is really hard to tell. Payton and Sanders were great despite playing for years with some pretty awful teams.

My brother is correct. Actually, if a back could get 2.51 ypc with zero variance, it would be evn better.

Anonymous said...

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