MLB players have met the robot strike zone. How's it going?

TAMPA, Fla. - In the third inning of the Grapefruit League opener on Feb. 21, Tampa Bay catcher Ben Rortvedt caught a full-count pitch from Eric Orze. The pitch to Yankees' Jazz Chisholm Jr. crossed the plate letter high and was called a ball.

MLB's great experiment was about to begin in Florida.

Rortvedt tapped his helmet, the signal to challenge the call, and home plate umpire Sean Barber stopped play. ABS was being called upon for an appeal.

For the first time in MLB, ball-tracking technology is making some ball-strike decisions during spring exhibition games. The move paves the way for one of the most radical changes in major-league history: so-called robot umps making ball-strike calls in real games.

MLB is currently testing a challenge system instead of full automation. Should it go well, the league could adopt the challenge system in the regular season as early as 2026.

Teams are each allotted two challenges during games played this spring in the 13 Arizona and Florida stadiums outfitted with Statcast pitch-tracking technology. The challenges can be made only by the batter, catcher, or pitcher. The dugout can't initiate one.

The challenges are designed to be decided quickly. In minor-league testing of this system in recent seasons, challenges averaged 17 seconds, according to MLB.

There's also no examining video from the dugout or clubhouse to aid challenge decisions.

Opinions vary so far, but players generally like being able to avoid having games turn on umpires' mistakes.

"When an umpire is missing 10 calls a game, it might be funny for fans, but it's not funny for us," Braves catcher Curt Casali said. "I know (umpires) are doing their best, but they are humans. They are going to miss calls. The difference in missing a strike or a ball could be the difference between a win or loss. I am all for us to have some ability to challenge ourselves and take control of our own at-bats. ... It would be a welcomed change."

After Rortvedt's challenge on Feb. 21, which took 32 seconds to complete, the replay showed the pitch missed the zone badly, perhaps by six inches. It was such a poor challenge that Rays manager Kevin Cash laughed in the dugout.

"He did a nice job," Cash quipped afterward. "Missed it by two feet."

Rortvedt said, "It's good just to get some feedback on the actual ABS zone and kind of see actually where things line up. ... Seeing actual pitches that cross home plate and how it's going to be done was pretty cool."

Some players in camps have experience with the automated system from the minor leagues. For many, though, it marks their first exposure to what might soon be in place in major-league games.

One of the biggest adjustments is that the zone called by umpires isn't a rectangle and tends to bulge in the middle. MLB research also found that the human strike zone tightens from 550 square inches in a 3-0 count to 412 square inches in a 0-2 count. ABS zones will be about 443 square inches for a player of average height.

Additionally, human umps are generally more lenient toward pitchers.

"It's a different zone, and we have to get used to it," Pirates designated hitter Andrew McCutchen said.

Pitchers' walk rates ballooned when various ABS approaches (full and challenge systems) arrived in the minor leagues in recent campaigns, according to Baseball America. At Triple-A in 2023, pitchers' walk rates spiked to 12%, the highest percentage in at least 60 seasons.

Of course, MLB could always tweak the zone's dimensions if it was too favorable to hitters. This spring, the zone's top-most boundary is 53.5% of a player's height, and the bottom of the zone is 27% of a player's height.

(Players were measured without cleats, standing straight up, by an independent training staff this spring and cross-checked by biomechanical assessments, according to MLB.)

While the system is more favorable for hitters, McCutchen said the benefits go beyond a tighter zone.

"I don't want full (ABS), but I like the challenge system," McCutchen said. "The challenge system is good because, eventually, the umpires will know the strike zone a little better. There is obviously some accountability for them, too. At the end of the day, that's what players want: we want accountability.

"You will see the umpires lock in more, which is what the guys say in Triple-A. The atrocious call that is not even close, they are not calling it. They are locking it in for 200 pitches. If they are missing it, it's going to be barely (off the plate). We are starting to see that already in these guys with a challenge system."

McCutchen is correct. The rate of missed calls within the strike zone declined early this spring.

The percentage of strikes called on pitches outside the zone dropped to 5.6% entering play Tuesday, a decrease from 7.2% last year and a Statcast-era low.

Called balls on pitches in the zone is 12%, down 0.6 points from last year's mark. That's another Statcast-era low for spring training games.

Catchers are most sensitive to any change in how umpires call the zone because it disrupts their ability to frame pitches and get favorable results on marginal calls.

"As a hitter, I want ABS. As a catcher, I do not necessarily want it," Phillies catcher J.T. Realmuto said. "It takes some of the art form of catching away. … It seems like it is devaluing the catching position."

Realmuto also wants a more limited challenge system over full automation.

With the challenge system, "you can still work pitches on the edges and steal some," Realmuto said. "Batters do not always know if it's that far outside, so they will not challenge it. It keeps some of the art of framing and presentation as part of the game.

"If we get full ABS, catch-and-throw will be most important, blocking will be more important. It would change the position."

Players say the challenge system will add elements to strategy. Teams get two challenges per game but can be right unlimited times. They only lose challenges when they're wrong. So, how early in the game will teams be willing to risk the first challenge?

"You don't want to use it in the first inning in a 0-0 count," Pirates backup catcher Jason Delay said. "You want to use it in counts that are more advantageous. ... In game-planning, you want one available for the seventh, eighth, and ninth innings. Use that first one, hold off, keep one in your back pocket.

"We are still learning."

There's also the question of which players should be allowed to use challenges - only key players or players who are good at judging the strike zone.

To avoid any assistance from the dugout or elsewhere, MLB is experimenting with broadcasters to remove the strike zone from some telecasts.

However, McCutchen believes removing the box from all broadcasts would make the game more entertaining if and when the system is implemented in the regular season. That way, fans can play along and second-guess calls.

While the technology might not be 100% today, it's likely far better than umpires' current accuracy rates on non-swing calls. The ABS is already creating more accountability.

Travis Sawchik is theScore's senior baseball writer.