During a game between the Tampa Bay Rays and the Milwaukee Brewers, umpire CB Bucknor had to be helped off the field after a foul ball hit his face during the first game of the MLB's Automated Ball-Strike Challenge System (ABS) Challenge System, which allows hitters, catchers, and pitchers to challenge balls and strikes for the first time, was a particularly bad night for Bucknor. Despite eight challenges over the course of the game, six of them were successful. The league rate for ABS challenges is 55 percent, while Bucknor's rate stands at 78 percent. According to measurements by UmpScorecards, Bucknor has been the least accurate umpire in Major League Baseball over the last five years by a significant margin. The site gives each umpher an expected accuracy score and measures how many correct calls above or below they make.