Why MLB’s Spring Training Challenge System Could Change Baseball — or Sink It Before Opening Day

Spring training has long been baseball’s laboratory—a place for rookies to find their groove and veterans to test new ideas without the crushing weight of October’s stakes. This time around, the experiment on deck is the Automated Ball-Strike (ABS) system, a video challenge mechanism that promises to redefine how we call balls and strikes. But here’s the kicker: unlike the pitch timer, which all teams embraced uniformly, ABS testing in 2025 feels a bit like that awkward family reunion where some show up ready to party and others are still stuck in traffic. Take Hunter Greene—fired a pitch he thought was a strike, only for it to be ruled ball four by a margin thinner than a hair’s breadth. He didn’t even bother to challenge it. Why? Because his manager told the big-leaguers to sit this one out, leaving the system’s backyard trial uneven and a tad fragmented. So, will the game’s oldest human element—the plate umpire—soon share the spotlight with a high-tech partner, or is this just spring training smoke and mirrors? As fans, we’re left wondering if this patchwork rollout will end with a roar or a whimper. LEARN MORE
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“We’ll see if the Reds decide to challenge with the ABS system …,” Cleveland Guardians TV announcer Matt Underwood started to say in the first inning of the spring training opener.

The smaller challenge system keeps the human element of the plate umpire intact while potentially decreasing human error.

The first challenge in the Reds at Guardians opener occurred in the fifth inning following a strike called against Cleveland’s Carlos Santana. The review overturned the umpire’s call to a ball, and when the graphic was shown on the stadium scoreboard, people in the Guardians dugout and the crowd laughed in unison.

Make no mistake, the Automated Ball-Strike System, or ABS, has proven results through the testing below the MLB level. Its technology creates a rigid definition of the strike zone that’s based off the height of the batter, and determines if a pitch crosses home plate within the strike zone. The batter, pitcher or catcher – not another player or the coaching staff – has two seconds to initiate the challenge of a ball or strike call he believes was incorrect.

The challenge system experiment can decide a spring training at-bat, and that may be particularly important to a minor leaguer seeking to produce strong results, but it doesn’t encourage major leaguers – such as the Reds – to train themselves on it or even risk the concept that an MLB umpire with a long memory will feel he’s being shown up by something that isn’t a part of the upcoming season.

Nope, the low, inside fastball was called ball four – not a third strike, as Greene anticipated.

Even if Hunter Greene doesn’t use it this spring.

Maybe by a few centimeters. Maybe not.

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Consider that the average MLB batter hit 60 points better with a 2-1 count than a 1-2 count in 2024 and 72 points better with a 3-1 count instead of it being 2-2.

Yes, it’s a huge difference.

It takes 17 seconds on average to confirm or overrule a ball or strike, according to MLB, so a challenge barely slows down the action. A graphic of the pitch and strike zone, showing the result, will appear on the stadium scoreboard and the broadcast feed.

Hunter Greene fired the two-out, 3-2 pitch, spun around as soon as it hit its target, and began to step toward his Cincinnati Reds dugout.

MLB commissioner Rob Manfred has long declared he wants an automated strike zone. Such a push, now sought for the 2026 season, may explain while testing moved forward in spring training without its method being apples to apples.

The technology is available in the home spring training stadiums – Grapefruit League and Cactus League – of only 19 of the 30 MLB teams. While all teams are part of the testing, the exposure varies, including the Arizona Diamondbacks having 29 ABS games and the Chicago Cubs just seven.

It appears the proverbial train is on the track and rolling along toward being implemented in a future MLB season, as Underwood suggested during the Guardians’ spring training opener.

The overall concept figures to be popular with major league baseball fans, who in recent years have embraced rules changes in the sport, including a pitch timer to speed up games. Many fans are even accustomed to a strike zone graphic during some broadcasts, with incorrect ball or strike calls by plate umpires suggesting a challenge system is overdue.

Each team is being issued two challenges per game during spring training games with the system, and one is lost only when the plate umpire’s call is confirmed.

Greene didn’t signal for the experimental video review that’s being conducted during spring training this year. Previously, Reds manager Terry Francona instructed the major league players on his team’s roster not to utilize the challenge system and fall back on something that won’t be a part of the 2025 regular season or postseason. He is, however, allowing the minor league players in camp to utilize the challenge system that’s been a part of some past minor league seasons, including Triple-A last year.

The video challenge system figures to be popular and make its way to a future MLB season. However, the testing method that’s occurring during 2025 spring training isn’t quite across the board, as, say, when players and coaching staffs tried out the pitch timer.

That difference stands out enough, but imagine if the Reds were the team with 29 games, and skipping on the MLB challenge system. The methods weren’t so varied when the pitch clock was experimented with in every spring training game.

That’s not quite the reaction desired by the plate umpire, or all umpires who still have to collectively bargain the challenge system’s implementation with MLB. But remember, there’s a lot more at stake here than simply the umpires’ pride. Each call can have a dramatic impact on the result of at-bat, and in turn, an entire game.
The challenge system is a heavily scaled-down version of a full ABS system, where every ball-strike call is automated and the plate umpire relays the outcome that’s been immediately provided via an earpiece. The “robo umpires” path would have major consequences for hitters, pitchers and catchers.