October 26, 2009 at 8:00 am by Capitol Avenue Club under Atlanta Braves, Pitching, Player Analysis, Statistical Analysis
Everyone knows (I hope) that pitchers’ ERA’s fluctuate a great deal more than their fundamental skills. Due to the pseudo-randomness of hitting singles, pitchers more or less have no control over whether or not a batted ball in play results in an out or a single. Doubles and triples are clearly different, but singles are–whether you want to believe it or not–mostly just luck. Whether a ground ball finds the hole between the 1B and the 2B or rolls right to the 2B, whether a shallow fly ball drops in front of the center fielder or falls into his glove, whether a broken-bat blooper gets over the SS or he’s able to make a jumping catch, these are all luck-based events. They’re lucky for a few reasons 1) the hitter wasn’t trying to do that. There wasn’t any skill, other than putting the ball in play, involved from a hitter’s standpoint. No hitter goes to the plate with the thought “I’m going to hit a weak fly ball and make it drop in front of the center fielder”. 2) It’s entirely up to the defense. The hitter and pitcher are out of the equation once the ball is put in play.
Therefore, the amount and rate of singles a pitcher gives up will fluctuate from year to year. Not because the pitcher has fundamentally gotten better or worse, but because of fluctuations of chance. Therefore, a pitcher’s ERA fluctuates similarly and parallel to the fluctuations in singles.
A metric called BABIP was created to model this phenomenon. Studies show that pitchers can’t control their BABIP, it’s a function of nothing they’re able to influence. It is calculated (H-HR)/(Balls put in play).
Which brings us to Derek Lowe and the hit-unlucky numbers he posted in 2009. They aren’t good, 4.67 ERA, 1.515 WHIP, 1.76 K/BB, etc. But Derek Lowe posted the 2nd highest BABIP in the NL in 2009–.333–leading to a league-high 232 hits allowed. While this isn’t a good thing by any means, it tells us something. If he can do everything he did and get a little luckier with the balls he allows in play next year, his numbers are likely to improve.
Bill James invented a metric called Component ERA, which attempts to determine what a pitcher’s ERA would be just from hits, walks, homers, etc. It’s abbreviated ERC. Derek Lowe’s ERC was 4.80 last season. However, if you adjust his BABIP from .333 to his career average (.295), he only allows 208 hits instead of 232. 24 hits doesn’t seem like a whole lot, but his ERC drops to 3.98 simply by removing those 24 hits. I’ve dubbed this aERC (adjusted ERC).
I think that 3.98 figure is probably what we should expect from Derek Lowe in 2010, though not just aERC, ERA as well. His FIP was 4.00 this season and if his fundamental skills hold steady and he has any luck at all, it’s reasonable to expect an ERA around 4.00.
2009′s numbers, on the surface, aren’t a true representation of Lowe’s fundamental skills. The smart money is on him bouncing back. Entropy exists in the universe, things have a natural tendency to regress towards the mean. The mean for Lowe isn’t 4.67, and we should see regression towards the mean–around 4.00–in 2010.