MLB to Use ABS Challenge System in Spring Training; Strike Zone Explained in Photos

Major League Baseball will experiment with the automated ball-strike challenge system in spring training games.

The league announced on Tuesday the ABS system will be used for roughly 60 percent of all spring games between the Grapefruit and Cactus Leagues.

The ABS system features a strike zone that is seventeen inches wide—the width of home plate—and it stretches from 53.5 percent of a player's height at the top of the zone to 27 percent of their height at the bottom of the zone.

MLB is using the system in spring training as a trial run to determine if it's suitable for regular-season games.

"This is a pretty big decision for the game of baseball," MLB executive vice president of baseball operations Morgan Sword said in the announcement, "that we want to get everybody to weigh in on."

Sword told reporters that the K-zone box used on television to show viewers an approximation of the strike zone could be reduced or removed from broadcasts altogether because it could be used to help aid the ABS system:

"The strike-zone box that we display on broadcasts and our app probably is inconsistent with the way we currently do it with the challenge system. You take a lot of the drama and excitement out of it if the fan can see up front that that pitch was a strike. It sort of obviates the need for the challenge.

"Then there’s a secondary issue, which is cheating. There are monitors, big-screen televisions all over our ballparks that display the feed of the game. And it wouldn’t be that hard if this box was up there for fans or anybody to yell to the players, right? That’s not what we want, either."

The ABS challenge system differs from a full-scale automated ball-strike system by keeping the initial ruling at the discretion of the umpire. They have the ability to call a ball or strike, but the Hawk-Eye technology that tracks ball, player and field position movement is also running.

If a player disagrees with the ball or strike call, they can ask for a challenge. The technology will then determine if the ump's call was right or wrong.

Challenges are limited to the pitcher, batter or catcher. No one else on the team, including the manager, can ask for a review of a ball or strike. The challenge must be made immediately after the initial call by the umpire.

For the experiment in spring training, each team will begin the game with two challenges each. Challenges are issued by a player tapping his cap or helmet. Teams will retain their challenges if they are successful.

MLB has been using the ABS challenge system in the minors since the 2022 season. It's been utilized during the All-Star Futures Game in each of the past two years.

While the ABS system won't be used for regular-season or playoff games in 2025, MLB commissioner Rob Manfred has said the league hopes to have some version of it in place by 2026.

The first game to feature the ABS challenge system will be Thursday's spring training opener between the Chicago Cubs and Los Angeles Dodgers at Camelback Ranch.