Robot umpires are getting their first MLB test during spring training

TAMPA, Fla. (news agencies) — A computerized system that calls balls and strikes is being tested during Major League Baseball spring training exhibition games starting Thursday after four years of experiments in the minor leagues.

Baseball Commissioner Rob Manfred is an advocate of the Automated Ball-Strike System, which potentially as early as 2026 could be used to aid MLB home plate umpires, but not replace them.

Starting in 2024, MLB focused testing on a challenge system in which the human umpire makes each original call. Data from the spring training test could cause MLB to make alterations to the system for Triple-A games this season.

Stadiums are outfitted with cameras that track each pitch and judge whether it crossed home plate within the strike zone. In early testing, umpires wore ear buds and would hear “ball” or “strike,” then relay that to players and fans with traditional hand signals.

The challenge system adds a wrinkle. During spring training, human umps will call every pitch, but each team will have the ability to challenge two calls per game, with no additions for extra innings. A team retains its challenge if successful, similar to the regulations for big league teams with video reviews, which were first used for home run calls in August 2008 and widely expanded to many calls for the 2014 season.

Only a batter, pitcher or catcher may challenge a call, signaling with the tap of a helmet or cap; and assistance from the dugout is not allowed. A challenge must be made within 2 seconds, and the graphic of the pitch and strike zone will be shown on the scoreboard and broadcast feed. The umpire then announces the updated count.

MLB estimates the process averages 17 seconds.

MLB has installed the system in 13 spring training ballparks that are home to 19 teams. The Florida stadiums, all in the Florida State League, are the stadiums of Detroit, Minnesota, the New York Mets, New York Yankees, Philadelphia, Pittsburgh and Toronto, plus the ballpark shared by Miami and St. Louis.