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Tuesday, October 06, 2009
Catcher’s strikeout rate
Jerry Crasnick:
According to Baseball-reference.com, Burnett has struck out 79 of 434 batters while pitching to Posada this season. Opponents are hitting .270 against Burnett and have a .775 OPS when Posada is his catcher.
In contrast, Burnett has struck out 77 of 288 batters while throwing to Molina. Opposing hitters have a .221 batting average and a .658 OPS against Burnett when he’s working with Molina.
Presuming that the quality of opposition is the same, we have a K rate of 18.2% with Posada and 26.7% with Molina. Figure an average of 350 PA. Burnett has a career K rate of 21.9%. One standard deviation, given 21.9% as the true rate and 350 sample PA is .022 K per PA. That puts Posada and Molina at roughly 2 SD from the mean (each going the other way, obviously). (The real numbers are 1.9 SD for Posada, and 2.4 for Molina.)
Again all other things equal, we see that Molina is the better catcher for Burnett. We can presume a non-zero difference. We CANNOT presume the actual observed performance.
Glove-slap: Michael