No umpire is perfect, and by and large Major League Baseball umpires call balls and strikes exceptionally well considering the speed and movement of big league pitches. However, key calls gotten wrong can turn a plate appearance—and even a series—on its head. Unfortunately for the Kansas City Royals, the umpires have benefited the New York Yankees with close calls in every game so far.
This is not merely the claim of a salty Royals fan, as the data is simply there. Umpire Scorecards is a group that does great work in evaluating umpire performance using the same Hawkeye tracking data that MLB uses for all their pitch statistic information.