Umpires Getting Better, Particularly at Calling Strikes

At its heart, baseball is a battle over the strike zone. As we can see from PITCH F/X data, umpires have been getting better at adjudicating this battle. From Noah Davis and Michael Lopez at FiveThirtyEight:

Umps are getting better, and they’re also remarkably consistent. An ump who makes more accurate calls in one year will likely do the same the next; an ump who misses more calls in a given season will likely be as bad the next. Umpire accuracy is more steady than a player’s batting average or a pitcher’s ERA, and as consistent as OPS (on-base plus slugging) and wins above replacement.

I would love to see an update about this and other data-driven topics to As They See ‘Em, which is a great book about umpiring that covers the history of the position, how they’re trained, what their jobs are like, and so on.