MLB to Implement ABS Challenge System League-Wide

Major League Baseball (MLB) has announced it will adopt its Automated Ball-Strike (ABS) Challenge System full-time starting in the 2026 season, allowing teams to challenge ball-or-strike calls made by home-plate umpires. Unlike fully automated umpiring, this hybrid system strikes a balance: the human umpire remains central, but select calls can be reviewed through technology.

Under this system, each team begins with two challenges per game. If the game extends into extra innings, teams that have used up their challenges will receive additional ones in the 10th and beyond. Challenges can be issued only by the batter, pitcher or catcher and must occur immediately after the call, without input from the dugout.

When a challenge is made, the call is reviewed using Hawk-Eye technology, with pitch tracking and zone data evaluated and relayed over a dedicated 5G private network. The result, either upholding or overturning the original call, is shown to both the stadium audience (via video boards) and viewers watching at home, with minimal interruption to the flow of play.

This decision follows years of testing: MLB deployed versions of the ABS system in minor leagues, at Spring Training and during the All-Star Game. The Joint Competition Committee voted in favor of this approach after considering feedback from players, officials and fans. One key outcome of that testing: the “challenge” variant was preferred over full automation, preserving the human dimension of umpiring and elements like pitch framing.

In practice, the ABS Challenge System is meant for critical calls, those that can materially affect an at-bat, rather than scrutinising every pitch. This narrowly targeted adoption is intended to correct clear mistakes while preserving rhythm, speed and human judgment in the game.

Statistics from Spring Training trials provide a preview of performance: an average of 4.1 challenges per game, with each review taking around 13.8 seconds. Overturn rates hovered above 50%, meaning that in many instances the technology corrected calls. However, teams only lose a challenge when the original call is confirmed, if a call is overturned, the challenge is preserved.

In designing this system, MLB aimed to maintain tradition while injecting corrective precision. The league views this as an evolutionary step, one that addresses tension between accuracy and the human element. Under ABS Challenge, umpires retain authority, while teams gain recourse when key ball-strike calls are in question.