MLB Ushers in Era of Robot Umpires with Automated Ball-Strike Challenge System
Major League Baseball (MLB) is set to revolutionize the game in the 2026 season with the implementation of an automated ball-strike (ABS) challenge system, often referred to as “robot umpires.” This marks the first time technology will be used in games to verify balls and strikes, representing a significant shift in how the game is officiated.
How the ABS System Works
The ABS system utilizes advanced camera and limb-tracking technology to create an individualized strike zone for each batter [1]. The system comprises four key subsets: the MLB tracking system, an interface for ballpark operators to set the correct batter, an MLB server for data processing and evaluation, and a low-latency communication system to relay calls to the umpire [1]. Measurements of each player allow the technology to render specific strike zones, rather than a generalized zone.
The Challenge Process
Teams will be granted a set number of challenges per game, which they can exercise at their discretion. Hitters, pitchers, and catchers can initiate a challenge by tapping their head [4]. If a challenge is successful, the pitch will be displayed on in-stadium videoboards, and the team will retain the challenge, mirroring the regulations for video reviews implemented in 2008 and expanded in 2014 [4].
Early Results from Spring Training
During the first day of spring training games in February 2026, just over half of the ball-strike challenges were successful. Thirteen of 23 calls were overturned across five games, resulting in a 56.5% success rate [2]. An average of 4.6 challenges were made per game, with 2.6 overturned calls per game [2]. In one game, seven challenges were made on calls by plate umpire Alex MacKay, with six being successful [2].
Testing and Implementation History
The ABS system underwent testing in the minor leagues, starting with select ballparks in 2022, and was introduced to limited spring-training ballparks in 2025 [1]. The Chicago Cubs made history as the first team to challenge a call during spring training in 2025 [1]. Previous testing in spring training in 2025 saw teams win 52.2% of their ball/strike challenges (617 of 1,182) [2].
Extra Innings Challenges
Teams that exhaust their challenges during the first nine innings will receive one additional challenge in each extra inning. Teams with remaining challenges will carry them into extra innings [4]. An additional challenge will automatically be granted in the 11th inning, and this rule extends for any subsequent extra inning [4].
Player Perspectives
Ian Happ, left fielder for the Chicago Cubs, expressed support for the ABS system, stating that the player group was predominantly in favor [1]. Jordan Wicks, a left-hander for the Cubs, noted that the system is primarily used for obvious missed calls and doesn’t significantly disrupt the game’s flow [1].