Robo umps in MLB? Inside baseball's latest ABS experiment

Laura Wolff/Charlotte Knights

CHARLOTTE, N.C. -- The pitch looked perfect. Thigh-high, 95 mph, right on the outside corner. Liam Hendriks was ready to celebrate a strikeout, and Roberto Alvarez was prepared to head back to the dugout, and then each was greeted with silence instead of a strike three call. Amid the quiet, one fan let his feelings be known. "Come on, blue, that's a strike," he yelled at home-plate umpire Cody Clark. And it was an eminently reasonable complaint, if not for one important fact.

It was a Thursday.

In Triple-A games this season, the day of the week matters. On Tuesdays through Thursdays, the strike zone is adjudicated by Major League Baseball's automated ball-strike system (ABS), which tracks pitches using a dozen ultra-high-speed cameras and spits out the result into an earpiece worn by the home-plate umpire in less than half a second. Even though Hendriks' fastball appeared to clip the edge of the zone on the digital rendering of the pitch seen in MLB's app and on its website, ABS deemed it a ball -- and the system, which the league says is accurate to less than one-tenth of an inch, is judge and jury.