Vladimir Guerrero Jr. and more players who should already be banned from ABS challenges

MLB's new ABS system is looking like a big win for everyone other than umpires who are not good at their jobs, and players who haven't had much luck challenging what they believe to be missed calls. The last thing anyone wants is for games to be won or lost thanks to poor calls by umpires, so the ABS system gives teams a chance to get the mistakes overturned. It also forces teams and players to be strategic when challenging calls.

Is it really worth challenging early in games? Is it worth letting everyone on your team have free rein to challenge calls? The answer to the latter question might be no, when discussing these players.

Vladimir Guerrero Jr., Toronto Blue Jays

On the surface, Vladimir Guerrero Jr. looks like the perfect player to use the ABS system as he pleases. Not only is he an MVP-caliber player with a terrific eye, but he also recently signed a $500 million contract. How can you tell your $500 million player that he can't challenge pitches? Well, the Toronto Blue Jays might not realistically be able to do that, but Guerrero looks like a player who perhaps cannot be trusted with the challenge system based on what he did in his first attempt.

Guerrero unsuccessfully challenged a 2-1 fastball in the bottom of the first inning with two outs and nobody on that nicked the inside corner. Getting the challenge wrong is one thing, but why did he even bother? Even if he had been successful, all that would've done is made the count 3-1 instead of 2-2. He wouldn't have reached base or gotten out either way. If this happened in the eighth or ninth inning that's fine, but is it really worth burning a challenge in the first inning?

Guerrero has an excellent eye, placing in the 90th percentile in chase rate per Baseball Savant in 2025. Still, no player has a perfect eye, and picking your spots has to be part of the equation. Guerrero isn't going to have privileges stripped, but a pattern of these miscues might result in a talk with John Schneider.

Yainer Diaz, Houston Astros

Catchers figure to be the most involved with ABS challenges as they can challenge calls both as a hitter and when they're behind the plate. Given their familiarity with the strike zone, most catchers have been successful when using ABS. Catchers have overturned 40 of 63 attempts thus far, good for a 63 percent success rate. Houston Astros catcher Yainer Diaz, though, has gone 0-for-2.

It's a small sample size, but nothing about Diaz's game suggests he has a thorough knowledge of the strike zone. He had a 44.3 percent chase rate in 2025, good for the second-worst mark among all qualified hitters.

Being a free swinger is one thing, but consistently chasing out of the zone suggests you might not have the best handle of the strike zone. The view behind the plate is different than that of a hitter, obviously, but nothing about Diaz's track record suggests he should be challenging many pitches.

Ronald Acuña Jr., Atlanta Braves

Five hitters have challenged more than one pitch thus far, and the only one to go 0-for is Ronald Acuña Jr. Now, to be fair, one of Acuña's failed challenges came in a fine spot to use one. It was a 2-2 count and the pitch to the former MVP winner just barely grazed the outside corner upon further review. 0-for-2 is 0-for-2, though, and Acuña's other challenge was not used responsibly.

Acuña challenged a 1-0 pitch in the Atlanta Braves' first at-bat of the game on Saturday, and upon further review, it caught a lot of plate. As mentioned in the Guerrero blurb above, what difference would it have made had that pitch been a strike? The difference between a 2-0 and 1-1 count isn't all that drastic, and it was only the first inning.

Acuña, like Guerrero, is too important a player to ever actually get ABS privileges revoked, but he might not be as good a player at challenging as a player with a good eye probably should be.

Javier Baez, Detroit Tigers

You knew he'd be here. Whenever the topic of hitters who chase comes up, it's hard not to think about Detroit Tigers' infielder Javier Baez, a player who swings at more pitches out of the zone than just about anyone. Baez's 46.1 percent chase rate was the highest in the majors in 2025 among qualified hitters, and he's consistently among the biggest chasers in the league.

Now, Baez won his first challenge of the year and won his only two spring training challenges (both in 2025), but even as a veteran player, is he really a guy you can trust? Teams only have two challenges - they must be used wisely.

Matt Wallner, Minnesota Twins

On the surface, Minnesota Twins outfielder Matt Wallner should be a player you can trust with the ABS system. He's known for being a three true outcome type of hitter, which means that while he strikes out a lot, he also hits a lot of home runs and draws a ton of walks. He's patient and has a pretty good idea of the strike zone. You wouldn't know that based on his latest challenge, though.

Up to bat with the bases loaded in the top of the seventh inning of a tie game, Wallner took a sinker that was clearly on the inside corner for a third strike. Rather than accept defeat, though, Wallner tossed his bat aside and immediately, out of frustration, challenged the call.

The pitch was clearly a strike, and there's a good chance Wallner knew that but let his frustration get the best of him. Players who are unable to control their emotions in big spots and are willing to waste challenges when an at-bat doesn't go their way probably shouldn't be allowed to challenge at all.

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