September 6, 2011

WAR Critique

It’s About the Money, Stupid publishes a critique of WAR. I found this part on fielding particularly interesting.:

So, I looked back at all teams that finished at the extremes of the flyball scale since 2003. I do not claim that there is a perfect or, in the parlance of economics, a “strong” correlation. That is, a team with a 35% flyball rate wouldn’t have a dramatic disadvantage in OF UZR compared to one at 38%. There is, however, significant evidence that pitching staffs with extreme batted ball tendencies can dramatically effect their outfielders UZR numbers. (These extremes I defined at upward of 40% at the high end and below 33% at the low end.)

Average OF UZR for FB% > 40.0: 10.1

Average OF UZR for FB% < 33.0: -10.6

I find this very interesting. Models like UZR and PMR should be measuring the probability of catching each individual fly ball, so lots of fly balls should not make an outfield good. I could imagine there is some selection bias here. General managers and field managers are pretty smart these days. They know the tendencies of their pitching staffs. So it’s possible that high fly ball staffs are backed by good outfielders by design. If you know a ton of fly balls get hit to the outfield, then the team should put good defenders there.

The whole article is well worth the read.

5 thoughts on “WAR Critique

  1. Bjoern

    It could also be that flyball pitchers get a higher percentage of their easy outs via the flyball. Where a groundball pitcher gets a weak roller to second, a flyball pitcher gets a lazy fly to medium center, everywhere else, they are identical. That would explain the effect, too.

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  2. Ed

    WAR, like Wikipedia, should be either the first stat or the last stat that you look at, but definitely not the only one.

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  3. Mitch

    It could also be a bias in the definition phase. Outfielders that are good would tend to catch more balls than those are not good, and caught balls are probably more likely to be labeled as “fly balls” and not “line drives.” So while it is very plausible that the selection bias above (fly ball pitchers require good outfielders) is correct, the stringer could also be influenced by whether or not the ball is caught.

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