Mar 25, 2026 - Major League Baseball opened its 2026 regular season on Wednesday with the debut of the Automated Ball-Strike Challenge System, allowing players to contest ball and strike calls using technology.
The system, known as ABS and powered by T-Mobile, uses tracking cameras to determine the precise location of pitches relative to each batter's individualized strike zone. Human home-plate umpires continue to make initial calls, but batters, pitchers and catchers can challenge them. Each team receives two challenges per game, with one additional challenge granted in extra innings. Successful challenges result in the call being overturned and the team's challenge retained.
The San Francisco Giants hosted the New York Yankees in the first game of the season at Oracle Park, marking the initial regular-season use of the technology. The ABS system was tested extensively in the minor leagues since 2022 and during Major League Spring Training in 2025. MLB's Joint Competition Committee approved its implementation for the full 2026 season and postseason last September.
The strike zone is defined as a two-dimensional plane across the full 17-inch width of home plate. Its height is tailored to each batter, extending from 27 percent to 53.5 percent of the player's height. The system operates on a private 5G network to deliver near-instant results during challenges.
Umpires retain authority over all other aspects of the game, including check swings and foul tips. Challenges cannot be used when a position player is pitching. The technology does not replace umpires but supplements their decisions on the most frequent calls in baseball.
Fans at ballparks and watching broadcasts will see real-time visualizations of the strike zone and challenge outcomes. League officials expect the system to improve accuracy on ball-strike calls while preserving the human element of the game. No immediate data on challenge success rates was available after the opening games.
As of Wednesday evening, multiple games were underway across the league with the new system in place. MLB reported smooth implementation during the early contests, with no technical disruptions noted. The full schedule continues Thursday with additional Opening Day matchups.