Boston University grad students analyzed more than four million pitches from 11 seasons of Major League Baseball (2008-2018), and the findings aren’t great for human umpires. According to the study, umps made 34,294 incorrect ball and strike calls in 2018. That works out to 14 blown calls per game and 1.6 per inning.

It’s not a huge number, compared to the 162 games each of the league’s 30 teams play in a given regular season, but it’s enough to give pause — and to confirm the suspicions that many irate spectators have had for years.

The study notes that the average age of MLB umps is 46, with an average of 13 years’ experience. Each season, umps call around 4,200 pitches behind the plate. Interestingly, the findings suggest that younger, less-experienced umpires tend to outperform vets.

The frequency of incorrect calls, perhaps unsurprisingly, tends to vary based on the nature of the play. Again, anyone who’s followed the game with any sort of frequency likely already had their suspicion that umps favor either the pitcher or batter, based on who’s leading in a count.

“Research results demonstrate that umpires in certain circumstances overwhelmingly favored the pitcher over the batter,” according to the study. “For a batter with a two-strike count, umpires were twice as likely to call a true ball a strike (29 percent of the time) than when the count was lower (15 percent).”

Notably, the news comes a month after the MLB announced that it would be exploring the use of robotic umps in the Atlantic League minors, with an eye on potentially implementing the technology in the majors at some point. The subject has gained prominence in recent years as baseball broadcasts now include a visualization of the strike zone.