A new study by Southern Methodist University researchers found evidence of implicit bias in baseball that “pushes the performance measures of minorities downward”.   The study found that umpires call strikes more often for white pitchers than for minority pitchers.

Researchers analyzed the calls of over 3.5 million pitches between 2004 and 2008 by major league umpires, who are overwhelmingly white, against the Quest Tec  computer system that uses four cameras to determine the speed and location of each pitch.  The researchers concluded that minority pitchers facing matched-race umpires will have 0.63% higher called strike probability than if they face non-matched-race umpires.  Minority pitchers react to umpire bias by playing it safe with the pitches they throw in a way that actually harmed their performance and statistics.

Johan Sulaeman, a financial economist and co author of the report reported that as a result of this bias minority pitchers were underpaid relative to white pitchers by between $50,000 and $400,000 a year.

“In MLB, as in so many other fields of endeavor, power belongs disproportionately to members of the majority – white – group,” the authors write.