The future is now.
With a new Major League Baseball season here, a major change will play a unique role in how the year progresses.
Coming to the majors this season is the Automated Ball-Strike Challenge System, or ABS for short. After many years of players and coaches resorting to ineffective arguing with umpires on controversial pitch calls, the technological advancement will aim to reduce human errors while adding new layers of strategy.
The system has been tested in the minor leagues since 2022, working its way up to MLB Spring Training games last year. It works similarly to the Video Assistant Referee (VAR) in soccer, but with slightly different regulations and team control.
It came into play on Opening Day, when New York Yankees utility option Jose Caballero lost the first ever MLB challenge when facing San Francisco Giants star Logan Webb.
Here’s everything to know about how the ABS Challenge System will work in MLB as it debuts in 2026:
What is ABS in MLB?
ABS stands for the Automated Ball-Strike Challenge System that is being used in baseball and coming to MLB starting in 2026. It helps to ensure important calls are being made correctly and offers balance between human umpires and previously incorporated “robot umps.”
How will ABS work in MLB?
The system monitors the exact location of each pitch, relative to the batter’s zone. Players can request a challenge on a ball or strike call that they disagree with, which can either be confirmed or overturned after a brief review. A graphic displaying the result will also be available for fans to view on the videoboard inside the respective stadium as the review unfolds.
Challenges will be available at every MLB ballpark, but not at the Mexico City Series, Field of Dreams game or Little League Classic, as those venues will not be able to support the technology.
Ballparks are also required to display the number of challenges remaining for each team using the code “ABS.”
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How many ABS challenges will MLB teams have? What about extra innings?
Each team will start the game with two challenges apiece.
If a game goes to extra innings, teams can get an extra challenge in the 10th if they are out. If they use it in the 10th, they can get another in the 11th and so on until the game concludes.
But if a team still has challenges left entering extra innings, they will not get another for that inning until it is used, if necessary. Then they’ll receive another for possible subsequent innings and so on.
Are successful ABS challenges retained?
Yes. But a challenge will be lost if the challenge is not overturned, so they must be used wisely.
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Who can issue ABS challenges?
Only the batter, pitcher and catcher can issue challenges, and it must be in the immediate aftermath of an umpire’s call (roughly within two seconds). Outside assistance is prohibited, even from a team’s manager. Umpires can refuse a challenge if they deem the call was aided by non-eligible teammates or coaches.
To issue a challenge, the player can tap their cap or helmet to alert the umpire, but are also encouraged to verbalize it if necessary.
In the event of technological issues, umpires can inform teams that challenges will not be allowed until the situation is resolved, along with an in-park announcement.
Are there any instances a pitch may not be challenged?
Challenges are not permitted when a position player is pitching or right after replay reviews, though it can be case by case.
How will ABS work on broadcasts?
It will remain up to broadcast networks on how they want to display the strike zone box on screens. The main change is that MLB is requesting broadcasters to no longer differentiate the circle in the box depending on whether the pitch is a ball or a strike.
Will ABS challenges be a statistic for MLB players?
Yes, Baseball Savant will include challenge statistics for players. For example, the catchers that are most successful not just at framing pitches but challenging calls will be available to dig through.
For more on the ABS and how it’ll work in MLB, click here.
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