Major League Baseball (MLB) is set to trial robotic umpires as part of a challenge system during spring training across 13 stadiums accommodating 19 teams, potentially leading to their implementation in regular-season games by 2026.

Since 2019, MLB has been piloting an automated ball-strike system in the minor leagues, yet it is still refining the parameters of the strike zone. For the robotic umpires to be adopted in the major leagues, an agreement must be established with the Major League Baseball Umpires Association, which is facing the expiration of its collective bargaining contract on December 1.

Baseball Commissioner Rob Manfred expressed interest in introducing the system by 2026, highlighting the need to negotiate terms as part of the employment conditions. After a meeting with team owners on Wednesday, he emphasized the necessity of evaluating the upcoming spring training trial before MLB makes further decisions.

Manfred noted the dual perspectives essential for assessing the trial, stating, “There’s two sides to that test. It’s what the clubs think about it, and also what do the players think about it? We’re going to have to sort through both of those.” This analysis is crucial in guiding the future of the automated system.

This year, Triple-A leagues implemented the automated ball-strike system (ABS) for the second consecutive season; however, there has been resistance to strictly enforcing the strike zone as delineated in the rule book. MLB has experimented with various modifications during the testing phase in minor leagues.

The current operation of the ABS determines strikes based solely on the ball’s intersection with the midpoint of the plate, measured at 8.5 inches from both the front and back. Adjustments this year include an increase in the strike zone’s upper limit to 53.5% of the batter’s height, up from 51%, while maintaining the lower limit at 27%.

Earlier this season, MLB began with a format that alternated between using the robot umpire for the first three games of each series and a human umpire with a challenge system for the subsequent three games during the initial 2.5 months of the Triple-A season. However, starting on June 25, the league shifted to a system allowing for human umpires who predominantly make the calls while incorporating a challenge mechanism.

During the latter half of the season, teams in the Pacific Coast League were allotted three challenges, while those in the International League received two, with successful challenges allowing teams to keep their attempts, akin to the video review system used in major leagues.

Manfred anticipates that the spring training experiment with ABS will offer valuable insights into how major league players interact with the challenge system. While the system may not be utilized in every stadium, a plan is in place to ensure that all teams will have significant exposure to the trial.