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Tuesday, October 11, 2011

Is Nick Swisher Overly Susceptible to Good Pitching?

I was thinking a bit more about the Nick Swisher graphic that Jonathan posted a few days ago.  It appeared to show that in the postseason Swisher saw a lower frequency of pitches in the middle of the plate and I was wondering if that was at least part of the explanation for his disappointing postseason performance as a Yankee.

Basically, what I was thinking is that Swisher tends to more damage against bad pitching and that he would do worse than expected against good pitching, assuming good pitching is better at working the edges of the plate.

I didn’t do a real rigorous study although I suppose whatever I see here may entice me to look at this in a bit more detail.

So here’s what I did.

1) Looking strictly at 2011, figure out the average wOBA allowed by the pitchers that faced Swisher, weighed to the number of PA Swisher had against them. 
  a) Take the pitcher’s overall wOBA against times PA vs. Swisher.
  b) Sum those up and divide by total PAs

The collective wOBA against by the pitchers that faced Swisher was .319.  MLB average was .314.

2) Take Swisher’s 2011 wOBA and compare that to the .319 average.  Using Baseball Reference’s data and ignoring SB/CS I get a wOBA of .354 for Swisher.  I haven’t adjusted for park or anything else.  So Swisher had a wOBA that was .354/.319 = 1.11 times better than what the average pitcher he faced allowed.

3) Think of a cutoff point to delineate “good” pitchers vs. “bad” pitchers.  This is somewhat arbitrary, but I set the cutoff so that 33% of his PA would fall against “good” pitchers, which in this case was pitchers with a wOBA against of less than .299.

4) Compare the ratio of his wOBA vs. good/bad pitchers to his overall wOBA ratio

Split	PA	wOBA	awOBA	Ratio
vs. .299<	221	.296	.277	1.07
vs. .299+	434	.391	.340	1.15
	655	.354	.319	1.11

What this table shows is that Swisher had 221 PA vs. pitchers who allowed a wOBA against of less than .299, and the collective wOBA against for those pitchers weighed by the times Swisher faced them was .277.  He had a wOBA of .296 against them, so his ratio was a bit worse than his overall ratio.  If you prefer to think of it in terms of standard deviation, a .354 wOBA hitter would have a range of .285 to .423 within 2 standard deviations over 221 PA, but looking at it that way ignores the fact that you shouldn’t expect a batter to hit as well vs. good pitchers, because, well, they’re good pitchers.

There’s not enough of a disparity here to make me think Swisher is especially susceptible to good pitching.  The difference between 1.07 and 1.11 is likely as much due to random variance as anything else.  Looking at more years might show a bigger gap, but I’m not sure it’s worth the hassle.

That’s not to say that there’s no reason that Swisher hasn’t performed in the postseason other than bad luck.  He may be pressing more and/or he may be teh unclutch or whatever.  But being exposed by better pitchers doesn’t seem to be the primary reason that he’s got an average wOBA of .370 over the last three regular seasons vs. an average wOBA of .265 over the last three postseasons.