The system has been around in the minors, but it makes it’s MLB debut in Spring Training.
If you’ve watched Minor League Baseball over the last few years, you’ll recognize what’s coming this Spring. The league has been testing and refining their automated ball/strike system in the minors and has decided it’s ready to make its MLB debut. They will also be using the challenge system rather than the fully automated strike zone, which is what most figure will be first implemented when ABS is brought to regular season games.
The system will only be available in 60% of Spring Training venues; in Florida, the ballparks for the Yankees, Blue Jays, Tigers, Pirates, Phillies, Mets, and the Cardinals/Marlins shared facility. The Twins’ second game of Spring Training will be at the Pirates’ spring facility, so Minnesota will get an early taste.
Want to see the automated balls and strikes system (ABS) in action?
Here’s Luis Gil challenging a call.
@ChrisKirschner pic.twitter.com/A5tYt6PAP4
— The Athletic MLB (@TheAthleticMLB) February 19, 2025
ABS Challenge Rules
Each team will have two challenges (separate from the existing manager’s challenges, which likely won’t be used in Spring games anyway). Only the batter, pitcher, or catcher can challenge a call, which they do by tapping their hat/helmet toward the umpire. If a challenge is successful, the team that initiated the challenge will retain the challenge. If the umpire’s original call is confirmed, they will lose that challenge.
MLB uses Hawk Eye tracking to model the zone and the pitch passing through it, just like in tennis. The result of the challenge can be determined nearly instantaneously, and both the players and the fans will be able to see the pitch model rendered on the video board during the challenge.
Contrary to what years of the white rectangle on TV have taught us, keep in mind that the strike zone is three dimensional. A pitch is considered a strike if it touches any part of that object at any point of the pitch’s flight. If Griffin Jax throws a slider outside of the zone at the front of the plate but clips the back corner thanks to some late break, that would still be a strike. This graphic from Fox Sports below has the exact zone measurements.
MLB is going to test the Automated Ball-Strike (ABS) challenge system during Spring Training games.
This was system was used in MiLB last year where calls challenged by players were overturned 51% of the time, per MLB.
What are your thoughts on the ABS Challenge System? pic.twitter.com/vraRdcf5WX
— FOX Sports: MLB (@MLBONFOX) February 19, 2025
MLB hasn’t made anything official, but the challenge system is widely expected to be implemented during the 2026 regular season. The league will have to negotiate with the umpire union before the move can be considered official, but with MLB backing off of a fully automated strike zone, that is largely a formality.
If you want more details on the ABS system and how it works, our old friend Al Yellon from Bleed Cubbie Blue has an extended video of MLB’s presentation in Arizona earlier this week.