Robo Umps Are Coming in 2026: MLB Approves ABS Challenge System

Robo umps are coming to Major League Baseball in 2026. MLB has greenlighted the ABS (Automated Ball/Strike System) Challenge System. This news was first reported by Joel Sherman of the New York Post, then later confirmed by the league.

The fact that MLB is willing to go with this system shows they are encouraged by the results. They tested it first in Spring Training and then in the All-Star Game. In both cases, there were very few issues with the operation. The All-Star game did have some very tight pitches that were overturned from balls to strikes that had an impact on the game.

Teams will have two challenges per game. A pitcher, catcher, or hitter is allowed to challenge. That process starts when one of the three players taps their head following a call.

The process takes roughly 15-20 seconds, with a nice graphic popping up on the scoreboard. If the call is overturned, they keep the challenge. They've been testing this system in the Arizona Fall League and Triple-A in recent seasons.

Bob Nightengale of USA Today adds that the 30 player reps voted 23-7 in favor of the challenge system. Arizona Diamondbacks ace Zac Gallen was one of the four players who are currently on MLB's Competition Committee. The way the committee is shaped (6 MLB representatives, 4 players, 1 umpire), the league can force any rule change they want.

What Some D-backs Have Said About ABS

In my time with Arizona Diamondbacks On SI, I had the chance to discuss ABS with some future Diamondbacks. Bryce Jarvis and Adrian Del Castillo were in favor of the challenge system over a full ABS.

I talked to Jarvis back in August 2023, just before his major league debut, for his take on ABS.

"I think if anything, it's more likely you'll see the challenge system. I find it a hard time believing that they'll go to the pure ABS like we have Tuesday, Wednesday, Thursday here in the PCL. I think some form of a challenge system might be around the corner. It's a matter of if they can get everyone on board."

When discussing the full ABS in April 2024, Del Castillo unsurprisingly preferred keeping the framing aspect of the game. The phrase he used was "you can't fool the computer" when discussing using a pure ABS approach. He described using those challenges as a "game within the game".

Debunking Misconceptions about ABS

• For ABS, a hitter's strike zone is based on their height, not their stance. So players who are tall and hit out of a big crouch (think Aaron Judge) will be penalized more at the top of the zone.
• Human elements such as framing and umpires calling balls and strikes will still be part of the game.
• The average umpire nails 19 of 20 calls (95%), on average. This season has also included two perfect games called behind the plate (Mark Ripperger and Nic Lentz).
• Full ABS will never be a thing in MLB. Given the accuracy of today's umpires, you probably need to challenge no more than 8 calls a game.