THE BOOK--Playing The Percentages In Baseball

Friday, September 21, 2007

Eric Gagne

If we look at his 2002-2004 data, we see the following totals: 202 GB, 187 FB, 108 LD.  This year, he’s 52/54/32, which is almost exactly in line with his 2002-2004 performance.  Nate Silver points out the enormous flip in GB to FB ratio of Eric Gagne, between Texas and Boston this year. Excluding bunts, in Boston, he’s at: 14/20/13.  If you divide his 2002-2004 data by 10, you’d get this expectation: 20/18/11, which means he’s given up a couple more FB, a couple more liners, and a few less ground balls.  When your sample size is 50, that really means nothing. Of his 14 groundballs, batters are 6 for 14.  But again, that’s 14 PA.  Of the 20 FB, batters are 6 for 20 (all extra base hits).  Of the 13 liners, batters are 11 for 13.  He’s given up 2 more groundball hits than he should have, a few more extra base hits than he should have and one more line drive hit than he should have.  In high-leverage situations though (LI of 1.8 or higher), opposing batters reached base 13 of 21 times, which is horrible.  But still, it’s only 21 PA.

All this to say that with some 70 PA, Gagne needs to be evaluated on his mechanics and pitch effectiveness, and not on the resulting batter performance.  Rereading Nate’s piece, he says exactly this, and he’s right:

There may be scouting evidence that Eric Gagne is not the same pitcher in September that he was in June. But there is little or no statistical evidence based on an informed reading of his numbers.