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Bad Aprils for Oakland A's hitters don't predict much

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You may have noticed that a few Oakland Athletics hitters are not doing so well at the plate. But fear not! A bad April is not a portender of a bad rest of the season. In fact, you'd do a lot better to stick with a player's preseason PECOTA projection as your projection for the rest of the season.

Here is every A's player with an OPS below .550 so far in order of how far that OPS is below their preseason PECOTA projection:

PA OPS thru Apr 20 PECOTA OPS Diff
Chris Coghlan 40 .541 .681 -.140
Coco Crisp 41 .535 .679 -.144
Billy Butler 22 .513 .741 -.228
Mark Canha 14 .500 .734 -.234
Khris Davis 49 .420 .758 -.338
Yonder Alonso 47 .301 .716 -.415

I hopped into the Baseball-Reference Play Index and found players who had at least 50 plate appearances in March/April and an OPS of .550 or below in that month who also had 150 plate appearances for the season between 2011-2015. I figure anybody who hit that poorly in the first month of the season but still got 50 plate appearances and then 100 more after that was a player who was expected to contribute.

This gives me a list of 148 player seasons. For each of these player seasons, I calculated the player's OPS after April, and then I compared it to PECOTA's preseason OPS projection. If it's the case that for the 30 or so worst regulars in April of each year, the more a player underperforms the more he would underperform in the future, we should see a strong correlation between the April underperformance and the rest of the season. Instead:

That's pretty all over the place, and in any event not close to a one-to-one correlation. Over the rest of the year, most will perform within 100 points of what PECOTA said their OPS was going to be.

That's not to say that players will outperform what PECOTA projected in order to "catch up" and hit that target. That's not what regression to the mean means. Regression to the mean is the concept that given infinite plate appearances, everyone will perform to their true talent. But since the baseball season is only six months long, a bad first month means that performing to one's true talent for five months inevitably leaves one a little bit short at season's end.

It might be the case that, for the rest of the season, a player happens to outperform what PECOTA projected his OPS to be or continues to underperform. But don't look to his April as a predictor that either of those outcomes will happen.

The best I can say is that for the rest of the season, Messrs. Coghlan, Crisp, Butler, Canha, Davis, and Alonso will probably perform within 100 points of what PECOTA said their OPS would be, and don't get overly bummed about a tough April. If you thought some of those players was going to be a very good hitter this year, don't let a bad April sway you from believing that from May through October. If you thought some of them weren't going to be that good, don't believe that player will be that bad the whole year through.