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Thursday, March 05, 2009

On the USA Today WBC Story

So I read the USA today article on pitchers.

My feeling is that it's in desperate need of controls and not particularly helpful. Quick thoughts.

1. 2006 is the highest-scoring year of the last five. Trying to point at ERA escalations in that year is a hard thing to do, because run scoring was up across the board. At least the authors did make some attempt to compare those pitchers to the overall MLB population, but they were inconsistent about it.

2. Perhaps more importantly, players chosen for the WBC were chosen in part based on the prior year. When you the players who have a good season that prior year, that sample of pitchers will be more prone to regress the next year than a random selection of pitchers.

Pitchers' ERA's vary a LOT from season to season, so if you choose the top-25 pitchers in a given year and compare their performance in the next season, that elite group will undoubtedly show a larger increase in ERA compared to a random sampling of MLB pitchers. This is classic regression to mean stuff. Maybe I'll run some examples tonight if I get in the mood.

3. Injury stats in that article provide absolutely no comparison to typical injury rates. To my eye, that makes their use border on dishonest and deceptive.

4. How much more were these players used compared to how they would have been used in spring training? How much more intense was the usage? I'm sure it's a bit higher (at least in intensity), but I'm frankly pretty skeptical that it's all that much higher.