MLB to Test “RoboUmp” System In Spring Training

Last July, I wrote that Robot Umpires might be tested during some 2025 spring training games, and now the technology has progressed to the point where the “Automated Ball-Strike System” or ABS will be in place for roughly 60% of this season’s spring training matchups.

The ABS System is not quite the same thing as having “robo umps” calling balls and strikes, although the system will allow for immediate challenges to ball/strike calls made by umpires. As noted by The Athletic (paywalled, unfortunately), “ABS relies on cameras to tell an umpire whether a pitch should have been called or a ball or a strike.” The system uses Hawk-Eye technology, which has been used in the Minor Leagues as well as other sports.

The new system will give teams the opportunity to challenge ball-strike calls that they feel the umpires may have gotten wrong (similar to official challenges already in place at the Major League level). Each team will have two challenges it can issue per game, and a team does not lose a challenge when it correctly asks for a review. One difference in the ABS and other official challenges is the immediacy of the challenge. Only the batter, the pitcher or the catcher can challenge an umpire’s call, and challenges must immediately be made after a pitch is called. No one else — not even the manager — may do so. To challenge an umpire’s call, players will tap their cap or helmet to indicate the review.

Once a challenge is made, the Hawk-Eye view is shown to those in attendance via the video board and to home viewers via the broadcast. In the minors, the challenge system added 17 seconds of game time, on average. Successful challenges are retained (meaning teams could in theory have an unlimited number, so long as they are correct), but is expected that ball/strike challenges will be used judiciously throughout the game, and may even be dependent upon the actual game situation. Players may be cautioned against challenging calls in “low leverage” situations (say, a 3-0 count in the first inning) since unsuccessful challenges count against the two each club is permitted.

Why, you may ask, would MLB test the ABS challenge system, as opposed to having Hawk-Eye call all balls and strikes? Per MLB

Minor League (MiLB) testing revealed a clear preference among fans, players, managers and other personnel for the challenge system. The reason, in so many words, is that fans and baseball people still desire a human element of umpiring that involves feel for the game. In MiLB games featuring full ABS, walks were more prevalent, causing games to drag on (and countering the improvements in pace made by the pitch clock).

Also, the art of pitch framing — a craft catchers have studied and in many cases mastered — would go away with full ABS. This is a change the players generally do not support.

Were full ABS to come to the big leagues, it would be hard to put the toothpaste back into the tube. The challenge system is seen as a way to get more of the most important calls correct without dramatically altering the sport overnight. It is a middle ground between full ABS and tradition.

MLB will not implement the ABS challenge system for 2025, but if the Spring Training experiments are successful, the system could be used in 2026 and beyond.

If you’re curious as to why MLB settled on two challenges per game, it is a compromise. At the MiLB level, MLB experimented with three challenges per team per game and two challenges per team per game. Three-challenge games had an average of 5.8 challenges per game, while two-challenge games had an average of 3.9 challenges per game. Per MLB, “In surveys of fans at Triple-A games, 71% said the optimal number of total challenges per game is four or fewer. Two-challenge games met this criteria 62% of the time, while three-challenge games met it only 30% of the time.”

One more interesting fact about MiLB testing: calls made by players challenging the call were successfully overturned only 51% of the time. According to MLB Executive Vice President of Baseball Operations Morgan Sword, “In no strike zone that we’ve tried, in no format that we’ve tried, has that rate moved much above or below 50%, which is pretty interesting in that these are the subset of pitches that are most ‘controversial’ among players.”

Most TV broadcast of MLB games now feature the “strike zone box,” which is of course unofficial, but which nevertheless still paints a pretty accurate picture of the strike zone (many broadcasts now include a “still” shot of where a pitch is located when it crosses the plate). It’s proven to be one of the more popular electronic enhancements to baseball broadcasts. And, it may end up as a casualty of the ABS challenge system down the road.

Per MLB:

That is enough of a concern that MLB is also going to use Spring Training to experiment with different ways of showing (or not showing) the strike zone on broadcasts. These will include showing the box but not the dot depicting the location of the ball, showing the dot depicting the ball but not showing the box, and showing only the corners of the box as opposed to the full box.

As noted when the league experimented with not showing the box at all during the All-Star Futures Game last year, there is also an entertainment incentive to not “give away” whether a pitch was a ball or a strike prior to a challenge, and the broadcast strike zones are inconsistent in their accuracy, anyway.

Of that, Sword said, “The strike-zone box that we display on broadcasts and our app probably is inconsistent with the way we currently do it with the challenge system. You take a lot of the drama and excitement out of it if the fan can see up front that that pitch was a strike. It sort of obviates the need for the challenge. Then there’s a secondary issue, which is cheating. There are monitors, big-screen televisions all over our ballparks that display the feed of the game. And it wouldn’t be that hard if this box was up there for fans or anybody to yell to the players, right? That’s not what we want, either.”

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A few quick thoughts.

In many ways, Rob Manfred is the worst commissioner MLB has ever had, but the changes he spearheaded in 2023 to speed up the pace of play have been excellent (pitch clock, number of times a pitcher can throw to a base with a runner on, allowing only one time out by batters during an at bat, etc.), so I’m a bit leery that MLB would implement a system which will slow games down. But in MiLB, the challenge happens pretty quickly. Once the ball gets back to the pitcher, the P.A. announcer informs fans that the call is being challenged, while the review is made. Within seconds an announcement is then made as to whether or not the call is upheld or overturned, and play resumes. If this challenge system results in a call within 17 seconds, as it has under MiLB testing, it shouldn’t add much extra time to a game.

I’ve grown quite accustomed to the strike zone box. While it may not be eliminated entirely, MLB will use spring training games to experiment on what works best to avoid using it to “cheat” to challenge an umpire’s call. Hence things like showing only the box (but not the location of the pitch) or showing pitch location but no box will be part of the spring experiment.

In recent years, pitch framing has become de rigueur for catchers, and has developed into something of an art. In fact, it’s altered the way many catchers set up behind the plate. I didn’t like it at first, but now I’ve grown accustomed to it, and indeed it seems some catchers are able to “steal” strikes based on their framing. The challenge system could have a profound impact on this art, and I wonder how long — if at all — catchers would need to alter their stances and mechanics. Most umpires aren’t fooled by pitch framing, but catchers are still taught to receive pitches this way.

I think the goal of the ABS challenge system is laudable — making sure balls and strikes are called correctly and offering teams the ability to challenge calls they feel the ump got wrong. But this is definitely something I’ll need to see in action. If it helps ensure correct calls and doesn’t significantly add to length of games, then I think it’s a worthwhile change. But that remains to be seen.

Your thoughts?