Strike Three: Do MLB Umpires Express Racial Bias in Calling Balls and Strikes?


Our paper on discrimination in baseball has finally been published (the June issue of the American Economic Review). While it received a lot of media and scholarly comment in draft, the final version contained a whole new section.  The general idea is that those discriminated against will alter their behavior to mitigate the impacts of discrimination on themselves.  But while reducing the impacts, these changes are not costless.  For example, if you’re an Hispanic pitcher and think that the white umpire is against you, you’ll change your pitches. Where will you throw? How will you throw?

The paper shows that the pitcher will avoid giving the umpire a chance to use his discretion in judging a pitch. More pitches go into the strike zone, more are clearly balls.  More are fastballs, fewer curves and change-ups.  A rational response, but by avoiding the umpire’s discrimination the pitcher makes it easier for the batter to hit the ball or to walk. Here’s the abstract:

Major League Baseball umpires express their racial/ethnic preferences when they evaluate pitchers. Strikes are called less often if the umpire and pitcher do not match race/ethnicity, but mainly where there is little scrutiny of umpires. Pitchers understand the incentives and throw pitches that allow umpires less subjective judgment (e.g., fastballs over home plate) when they anticipate bias. These direct and indirect effects bias performance measures of minorities downward. The results suggest how discrimination alters discriminated groups’ behavior generally. They imply that biases in measured productivity must be accounted for in generating measures of wage discrimination.


And here’s a graph showing called strikes by distance from home-plate center. Data from 2007-2008 (N=144,990)



Cue all the posters who will insist that racism doesn't exist.

Joshua Northey

Umm what serious person claims it doesn't exist?

Sam Reaves

In what years was this study conducted?

D Walt

"...those discriminated against will alter their behavior..." EXACTLY! and as in baseball, so is it in life, and at what cost? A pitcher loses his unpredictable approach, his off balance pitches, his full arsenal & uniqueness...what does a person in society lose? Great study.


There aren't that many black pitchers in the MLB right now compared to Hispanic, white and oriental. This makes the group as a whole prone to skewing from outliers like Edwin Jackson who throws alot of innings and alot of balls. This is just seems like another study that fails the causation/correlation test.





Daniel H.

Haven't had time to read through the whole study yet, but a couple things stand out to me at the start. First, the ballparks where the QuesTec was installed are those of the Anaheim Angels, Arizona Diamondbacks, Boston Red Sox, Cleveland Indians, Oakland Athletics, Milwaukee Brewers, Houston Astros, New York Mets, Tampa Bay Devil Rays, Chicago White Sox, and New York Yankees. Based on their rosters from a couple years ago, this group of teams would have, on average, better pitching than the league as a whole, or the non-QuesTec teams. Second, teams that have better attendance also have, in general, better pitching. Seems like that would skew the data toward seeing more called strikes at these ballparks, not necessarily because the umpire is more conscious of monitoring, but because the pitchers simply have better control and the ability to fool batters into not swinging at strikes.

Michael Peters

But why would that matter? We're not comparing big teams to little teams (or QuesTec vs non QuesTec), we're comparing racial makeup of pitchers and umpires.


Study should be called "Douche bag white kids from major metro-areas with multipile college degrees who have major white guilt and have way to much time on their hands because they can't find steady work because they are over qualified for any job they interview for"

A Nother

What about the batter's race? The pitcher isn't the only player either advantaged or disadvantaged by the ump's call on a close pitch. I think if the data showed any pitch was as likely to be called a strike when the pitcher and batter were of the same race as when the batter and the umpire shared a race different than the pitchers, that would tend to negate the researchers' theory that discrimination plays a role in the way these games are called. I'd tend to give the home plate umps the benefit of the doubt, considering the volume of calls they're required to make in a given game/series/season.

paul o.

Maybe foreign-born Hispanics pitchers just have more cajones than U.S.-born White pitchers. Take Carlos Zambrano of the Cubs for example, a very in-your-face sort of guy. Foreign-born Hispanics have less to fall back upon than White players with a college education. A timid Hispanic guy probably doesn't get a contract if he has the exact same skill set as a White player.


What this study doesn't take into account is that while grouping hispanics as a whole it is not taking into account the differences between guys from Puerto Rico, Venezuela, República Dominicana, Cuba and México. There is a lot of envy/jealousy between hispanics. Puertoricans see the rest of hispanics as inferiors because they are considered US citizens, while Cubans will always think they are the best race to ever play baseball. Jealousy between mexicans its also obvious for those mexicans born in the US towards mexicans who come from México (in México you are a mexican independently of where you were born if one or both of your parents is a mexican citizen or was born in México).

In that regard, i am mexican, but also consider Márquez as the worst umpire right now, he has shown a propensity to call balls/strikes as he sees fit, specially if a pitcher has a no-hitter, he will expand the strike zone and reduce the strike zone to the visiting team.



Learn from the far superior sport of cricket or even tennis and employ a tracking technology called 'Hawkeye'.

Nate W.

I haven only skimmed through the study, so there is a good chance this may have been addressed in the paper, but I'm wondering if/how the authors addressed the errors in the system for judging the strike zone. This reminded me of an article I read back in March from Baseball Prospectus about the accuaracy of the PITCHfx data. You may need a subscription to view the link. It would be difficult to summarize it here, the jist though is that (sometimes significant) errors occur in systems for judging the strike zones (PITCHfx, K-zone, QuesTek, etc.)


On the wage discrimination discussed at the end of the full article. It appears that you haven't differentiated between subjectivity of the evaluator affecting measured output and it affecting actual output. For example, with piece work a worker may make one hundred widgets but his boss syas there's only 90; so measured performance varies from actual performance. With baseball the subjectivity affects actual petrformance; if the umpire says it's not a strike, it's not a strike. Therefore, if there's a bias against minority pitures, this will affect there actual performance and you'd expect them to be paid less.


What about the race of the batter who is up at the time?
Is that factored in?

And do you differentiate the pitcher's perception or prediction of bias from an umpire versus any actual bias of an umpire? It's a little unfair to imply that a specific umpire "A" is biased simple because a pitcher behaves as if he expects that umpire to be biased.

If a white woman crosses the street to avoid a black man, it doesn't make that man a thug. It only describes her perception.


Do you think baseball manufacturer's hire Haitian witch doctors to cast a voodoo spells on the balls so Hispanic and Black players have a better chance at hitting them?
The whole premise, study and article is idiotic.
There are good umpires, and better umpires. They all make mistakes sometimes.