Baseball is about to change forever, and your Grandfather is going to hate it.
Starting in 2026, MLB is rolling out its Automated Ball-Strike (ABS) Challenge System across the big leagues. This is NOT ROBO UMPS. This is a challenge layer on top of the human umpire, and I think it might be the greatest change MLB has made in a decade.
In This Blog
ABS is a challenge system, not full automation
Who can challenge + how it works (and how many you get)
What the “ABS strike zone” actually is
Pace-of-play impact: Does it slow games down?
Strategy + what fans should watch for in 2026
1) ABS Is A Challenge System, Not A Robo Ump
Let’s kill the biggest misconception first: ABS does not replace the home plate umpire.
The plate ump still calls balls and strikes. ABS only steps in when a player challenges a call, and then the broadcast/scoreboard shows the result almost instantly. In that time, the umpire steps away and announced the call and that there is a challenge. We have seen a number already this Spring, and they move very fast.
Full automation would basically nuke the human part of calling a zone and the entire craft of pitch framing, which would throw a lot of new statistics into flux. The challenge system keeps the human element while cleaning up the most egregious misses.
2) Who Can Challenge?
Only three people can do it:
Batter
Catcher
Pitcher
The player has to challenge immediately after the pitch, and the official signal is a tap on the cap/helmet. Any longer and the ump will not accept it, as there is a fear of signals coming from the dugout.
Two per team to start the game
You only lose one if the call stands (win the challenge = you keep it)
If you’re out of challenges and the game goes to extras, you’ll get one challenge for that inning (10th, then 11th, etc.). If you already have at least one challenge left entering the 10th, you don’t get a bonus one for that inning.
3) What the ABS Strike Zone
Width: 17 inches — full width of home plate.
Top: 53.5% of the batter’s standing height.
Bottom: 27% of the batter’s standing height.
Plane: Measured at the midpoint of the plate (8.5 inches from front and back), as a flat 2D rectangle (unlike the rulebook’s 3D zone).
It of course adjusts to the batter and everything is digital and very accurate (thus far).
4) Does ABS Slow The Game Down?
Nope.
From MLB’s spring training testing, challenges averaged 13.8 seconds, and games averaged about 4.1 challenges, so you’re looking at roughly a minute of added time in a typical game.
That’s why MLB feels comfortable adding this on top of the pitch clock era: it’s not a full-blown replay review where everyone stands around for three minutes while New York debates rules.
5) STRATEGY: When To Use It
Feels obvious but….
Full-count pitches
Strike three / ball four moments
Late innings with runners on
MLB’s own spring data showed catchers doing better than hitters on challenges overall. To that point, a number of pitchers have already come out and said they will not use the challenge system at all. We have also seen a lot of teams just hold them until the end of the game and then use them in the final two innings.
A huge chunk of MLB ejections has been tied to ball/strike disputes, and one of the motivations for ABS is to reduce that constant friction.
Quick FAQ
Is ABS in every MLB game in 2026?
It’s in every game at an MLB ballpark, plus the postseason.
Do managers get to challenge balls and strikes?
No! Only the batter, pitcher, or catcher.
Do you lose a challenge if you’re right?
No, you keep it if you win.
How fast does a challenge have to happen?
Immediately after the call.
I don't like substituting a 2D strike zone for the 3D zone in the rule book. And that change will apply only to challenges, not to the zone the umpire calls.
If a pitcher drops a big overhand curve ball in the back of the strike zone, the batter may challenge in order to change the strike zone, not to correct an erroneous call.