MLB will adopt the ABS Challenge system beginning on Opening Day for the 2026 season.
How it works/some things to know about the system:
Each team will get two challenges and can keep them if they're successful.
Challenges can only be initiated by a pitcher, catcher or batter, and the request must come right after the pitch.
To signal a challenge, the pitcher, catcher or batter will tap his hat or helmet to let the umpire know. No help from the dugout or other players on the field is allowed.
If a team enters extra innings without a challenge, they'll be given an extra one every inning. The challenges will not accumulate if not used. Teams will never have more than one challenge per extra inning unless they entered extra frames with their original two intact.
Umpires will be given discretion on plays that happen on the bases, even when a pitch is being challenged. For example, the outcome of a stolen base attempt is likely to stand no matter the outcome of the challenge, with the lone exception coming on a ball-four or strike-three call that is overturned. If the umpire deems "player behavior" has been impacted -- for example, if the catcher stops playing because he hears ball four and the call is overturned -- he might send the runner back to his original base and the stolen base won't count.
A pitch may not be challenged if a position player is pitching.
It's possible for both an ABS challenge and video replay challenge to occur on the same play. If that happens, the ball-strike call will be adjudicated first, followed by the video replay on the bases.
The Strike Zone:
The league is measuring the standing height of each player to determine their individual strike zone, which will be slightly smaller than the umpire called zone. The ABS zone for each player is based on measurements taken by one independent party and verified by another; the top of the zone is defined as 53.5 percent of a player’s height and the bottom of the zone is 27 percent of their height. The zone is 17 inches wide -- the width of home plate -- and pitch location is measured at the midpoint between the front and back of the plate. Any part of the ball only needs to tick the edge of the zone to be a strike.
The league changed the height criteria several times while experimenting in Triple-A games over the past three years.
Data shows from MLB’s 288-game experiment in spring training in 2025, calls were overturned 52.2 percent of the time; catchers had a 56 percent success rate, compared to 50 percent for hitters and 41 percent for pitchers. There was an average of 4.1 challenges per game, and those challenges took an average of 13.8 seconds.
A pitch may not be challenged if a position player is pitching.
Seems like an odd rule to include. If position players are pitching, the game is usually out of hand and no one is concerned with how accurate calls are at that point.
A pitch may not be challenged if a position player is pitching.
Seems like an odd rule to include. If position players are pitching, the game is usually out of hand and no one is concerned with how accurate calls are at that point.
Wouldn't that be why they're including it? Games out of hand, umps are going to open up the zone.
A pitch may not be challenged if a position player is pitching.
Seems like an odd rule to include. If position players are pitching, the game is usually out of hand and no one is concerned with how accurate calls are at that point.
Wouldn't that be why they're including it? Games out of hand, umps are going to open up the zone.
But when would a pitcher, catcher, or batter ever challenge it at that point? Just seems like a really odd detail to include, when it might be one extra challenge every 5 years.
A pitch may not be challenged if a position player is pitching.
Seems like an odd rule to include. If position players are pitching, the game is usually out of hand and no one is concerned with how accurate calls are at that point.
Wouldn't that be why they're including it? Games out of hand, umps are going to open up the zone.
But when would a pitcher, catcher, or batter ever challenge it at that point? Just seems like a really odd detail to include, when it might be one extra challenge every 5 years.
IDK, to be a dick if you're the hitter. To make a mockery of the rule if you're the catcher. Because they can if you're the backup RFer now pitching. Actually, that's probably the most likely. All of them being wastes of time with no impact on the outcome of the game. A white flag would be something. I doubt fans would be happy if the game ended after 6 innings or whatever though. And it would impact the rules of selling alcohol. IIRC Busch Stadium stops beer sales in the 7th inning. Imagine trying to add a run limit to that as well.
Are these the same exact rules they've been using in the minors?
It seems like it will be working exactly the same as the minors; though I am not sure if the minors have some of the rules like position player pitching etc.
This seems like a bad idea. Why not just go full Roboump?
I have seen it in use at minor league games and it is just fine. We shouldn't need robo umps. This will fix egregious calls and also help standardize the zones a bit as umpires get used to the system/older umpires retire etc.
