So Not Even Umpires Fairly Call Balls and Strikes

July 7th, 2014

Paging Chief Justice Roberts: Umpires give more favorable strike calls to All-Star pitchers:

Two researchers looked at the photographic evidence and found that umpires make more errors in favor of All-Star pitchers than in favor of pitchers who have never been to an All-Star Game — about 17 percent more. …

But the science exists, for anyone who wants to look at it. Every major league stadium is equipped with the Pitch f/x system, which includes strategically placed cameras that record the locations and trajectories of every pitch. The technology provides a record that is difficult to dispute. In the seasons the study covered, 2008 and 2009, umpires earned a B-plus average, at best, in calling balls and strikes.

The researchers — two business school professors, Jerry W. Kim of Columbia Business School and Brayden G. King of Northwestern’s Kellogg School of Management — looked at data on 756,848 pitches over 313,774 at-bats in 4,914 games. Some umpires were, unsurprisingly, more accurate than others, but on average they called a strike on 18.8 percent of pitches that were actually out of the strike zone and a ball on 12.9 percent of pitches that were, in fact, strikes.

Many factors besides All-Star status could affect an umpire’s judgment, so the researchers adjusted for the home team advantage, the importance of the at-bat to the outcome of the game, the count at the time of the pitch, whether the pitcher or the hitter was a lefty or a righty, the catcher’s ability to frame a pitch and make a ball look like a strike, and even the size of the crowd.

But after controlling for all these variables and more, the advantage gained by a pitcher’s status was still large. For each additional appearance in an All-Star Game there was a 4.8 percent increase in the probability that an actual ball would be called a strike. A player with five All-Star appearances had a 14.9 percent chance of a true ball being called a strike, which is a 16.7 percent increase over the chance a journeyman will benefit from the same mistake.

The error is not just the result of All-Stars being around the plate more than other pitchers. Even on the identical pitch just outside the zone, All-Stars got the call when journeymen did not.

With miscalled strikes, the same thing happens in reverse. A pitch in the strike zone thrown by a journeyman has a 19 percent chance of being called a ball. For the All-Star, the probability drops to 17 percent. That may not seem like a lot, but it means that an All-Star gets an automatic 9 percent advantage based not on his performance but on his reputation.

Although the effect is somewhat weaker, the same kind of bias appears when an All-Star batter is at the plate. The researchers calculate that a five-time All-Star has roughly a 5 percent or 6 percent advantage in getting a favorable ball-strike call.

I wonder if, similarly, the Justices give better treatment to Supreme Court veterans, who routinely argue cases. I suspect that if a newbie pulled the stuff Tom Goldstein does, he would be heaved out of Court.