With opening day now less than two weeks away, Major League Baseball is preparing to unveil one of the most significant rule innovations in recent memory: the Automated Ball-Strike (ABS) Challenge System.
After years of testing in the minor leagues and during spring training, the system will debut during the 2026 regular season, giving players the ability to challenge ball and strike calls made by the home-plate umpire.
The ABS Challenge System is designed to strike a balance between technology and tradition. Rather than replacing umpires with fully automated strike calls, MLB opted for a challenge-based format that allows players to contest only the calls they believe were incorrect. The goal is to correct key mistakes while preserving the human element that has long been part of the game.
The technology tracks the exact location of each pitch relative to a batter’s personalized strike zone. If a player believes a call was wrong, the pitch location can be instantly reviewed and displayed on the stadium videoboard and television broadcast.
Each team begins a game with two challenges. If a challenge is successful and the call is overturned, the team keeps the challenge. If the umpire’s call is confirmed, the challenge is lost. Teams that run out of challenges during a game that goes into extra innings will receive an additional challenge at the start of each extra frame.
Only the batter, pitcher, or catcher may challenge a call, and the request must be made immediately after the pitch. Players signal a challenge by tapping their helmet or cap and verbally alerting the umpire. Managers and other players cannot initiate a challenge, and teams are not allowed to use input from the dugout.
When a challenge is issued, the pitch is analyzed by the ABS system, and the result is shown through an animated graphic. The process happens quickly. Testing during 2025 spring training showed that challenges took an average of about 13.8 seconds to resolve, adding less than a minute to the average game.
The system will be used in all MLB ballparks throughout the regular season and postseason. A few special events played outside of major league venues — including the Mexico City Series, the Field of Dreams Game, and the Little League Classic — will not use the technology because the infrastructure is not available.
The strike zone used by the system is tailored to each batter’s height. The zone spans the width of the plate and is calculated from 53.5 percent of the player’s height at the top to 27 percent at the bottom. Players’ measurements are taken before the season to ensure accuracy.
Testing showed the challenge system had little effect on the pace of play or the number of pitches per plate appearance. However, the slightly different strike-zone geometry may produce marginally fewer strikeouts and slightly more walks.
Spring training feedback has been largely positive. Surveys conducted by MLB found that 72 percent of fans said the system improved their viewing experience, while a majority of players and coaches preferred the challenge format to either full automation or traditional umpire-only calls.
Because challenges are limited, strategy will become part of the equation. Players must decide when it is worth risking a challenge, particularly in high-leverage moments late in games.
Source: MLB