What is MLB’s New ABS Challenge System?

Starting in the 2026 season, Major League Baseball will introduce the Automated Ball-Strike (ABS) Challenge System.

It marks the latest change in an ever-evolving game that most recently had success with the pitch clock. MLB is hoping the ABS will be just as successful, leading to more efficient calls on the game’s most important plays.

But how does it work? Well, allow me to provide a quick guide for all things ABS.

What is ABS in MLB?

MLB’s Automated Ball-Strike (ABS) Challenge System allows players to contest a home plate umpire’s strike-zone call. The system uses Hawk-Eye tracking technology to measure the precise location of a pitch in relation to the batter’s strike zone.

After the umpire makes a call, a player can immediately challenge it by tapping their helmet or cap to signal the umpire. The decision must be made right away, without input from the dugout or teammates.

When a challenge is issued, the ABS quickly reviews the pitch. Fans in the stadium will see an animated graphic of the pitch result on the video board, and television viewers will see the same animation during the broadcast.

The entire review process is designed to be completed within seconds of the pitch.

Who Can Issue an ABS Challenge?

For a given pitch, three players can challenge an umpire’s call on a ball or strike:

• Batter
• Pitcher
• Catcher

Nobody else on the field or in the dugout can issue a challenge via the ABS.

How Many Challenges Does Each Team Get?

Each team will begin the game with two challenges. A team keeps its challenge if the review is successful. A challenge is only forfeited when the umpire’s original decision is upheld.

If a game goes into extra innings, any team that has used all of its challenges will receive one additional challenge at the start of an inning. However, a team will not be awarded an extra challenge if it still has one remaining.