ABS Challenge System - The Secondary Effects

[amjgt]

I like the direct effects of the ABS challenge system. Adding a layer of strategy. Getting more calls right. And probably adding a little bit of time to the game length in order to have those things happen.

But its the secondary effects that I think are WAAAAAY more interesting and something I've been thinking about a lot. If there's an advantage to be gained players will try to gain it. If there's a new thing to be measured, people will try to measure it. Here are the big ones in my mind. I'd love to hear other thoughts and ideas on this.
 

1.    Length of game – I think this has maybe been overstated a little. The actual time it takes to do the challenge is 10-15 seconds. We are, at most, adding like 2 minutes to game length, directly from the time it takes to perform the reviews. HOWEVER… we don’t yet know if it is the pitcher or the hitter who is going to end up with an advantage over a large sample. If the pitcher ends up with the advantage, then offense will trend down slightly, and the games will shorten. If the batters end up with the advantage, then the opposite will be true. It's hard to say which way it’ll go at this point and it might be a little bit team dependent, depending on how they allow their players to deploy the challenges

2.    The strike zone – There’s a lot here. All players have been physically measured and so now they all have their own unique strike zone within the ABS system. They’ve all theoretically had unique strike zones up to this point, but that relied on the umpires to make adjustments on the fly and I suspect that they didn’t fully account for the size difference between, say, Jose Altuve and Aaron Judge. Do smaller players now get to fully realize the strikezone advantage they should’ve been getting this whole time? Does Emmanuel Rodriguez's small stature and good eye at the plate give him and even larger advantage that he's been seeing in the minor leagues up to this point? How does digging into the box affect things? It doesn’t take long into a game for there to be a hole in the batters box. Given that the strikezone will be based on the height of the plate, not the height that the player is standing at, is there an advantage to be gained by “digging in” an inch or two below the level of the plate. The new measured strike zone would go from the top of the knee, to now higher up the leg. This would help players that struggle with low strikes and have the opposite effect on players that struggle with high strikes. Will MLB regulate the amount of digging into the batters box that players are allowed to do? What about cleat length?

3.    Catcher metrics – Pitch framing is no longer quite as important, but will there be a new metric of “Catcher Judgement?” I think most people agree that the catcher is in the best position to accurately judge whether a pitch was incorrectly called a ball. I’m envisioning two new measurements. A) challenge accuracy. This one is simple. How many challenges did they call for and how many of those were correct, but B) one more layer deep we will be able to analyze how many calls they SHOULD have challenged and the leverage of those pitches. You’d love to correctly challenge every missed call, but a missed 0-0 pitch that just clips the corner isn’t nearly as impactful or as big of a miss as a missed strike 3 call that caught a lot of the plate. "Catcher Judgement" feels like it's going to be a massively impactful statistic. Also, Catcher receiving position has been a hot topic the last few year. Mostly, I believe, catchers have tried to get lower behind the plate, in order to get more low strikes called. Does that matter as much any more? Will catchers go back to a more traditional crouch because it gains them back a slight advantage in throwing out runners?

 

All of these things are very interesting to me. I'm sure there are other ones I'm not thinking of and I look forward to the answers we get over the course of a full season. 

[FlyingFinn]

With some teams, if the catchers show great judgment on which pitches to challenge, I think they wouldn't allow most of their pitchers to challenge. 

[Linus]

I’ve watched parts of three games and the catchers haven’t been wrong yet. Brian O Nora had about a dozen challenges against every one was upheld. I really hope the catchers go back to a traditional crouch. Better for throwing and blocking. 

[ashbury]

3 hours ago, amjgt said:

HOWEVER… we don’t yet know if it is the pitcher or the hitter who is going to end up with an advantage over a large sample.

I know of a strong argument in favor of offense going up: pitching is all about disrupting the batter's approach and anything that makes that part of the game more predictable will aid the batter.

I don't know of a countervailing argument that would give the pitcher any edge.  If the umpires were systematically calling balls when they should be strikes, more often than the reverse, then maybe, but I'm not aware of any studies showing that.

[amjgt]

The argument I'd make against that point is that the person most equipped to consistently make correct challenge decision (the catcher) is on the side of the pitcher. 

That advantage (of catcher/pitcher vs hitter) MIGHT be so stark that teams don't even really want their hitters triggering ABS challenges because of the much higher likelihood that they are wrong and they don't want their catchers to lose that ability going forward in the game. It could be that they only allow the hitters to challenge in truly extreme leverage positions, whereas, as the catchers prove out their ability to be correct a high percentage of the time, they have a much longer leash in terms of when teams allow their catchers to challenge. 

Said another way... Just because, if looking back at old data, the misses that umps make tend to be more likely balls that were called strikes (calls batters would challenge), doesn't mean that those are the calls more likely to be correctly challenged. It could be that catchers would also be really good at identifying those calls, but they are, of course, not going to challenge calls that have benefitted the pitcher. 

 

[nicksaviking]

1 hour ago, ashbury said:

I know of a strong argument in favor of offense going up: pitching is all about disrupting the batter's approach and anything that makes that part of the game more predictable will aid the batter.

I don't know of a countervailing argument that would give the pitcher any edge.  If the umpires were systematically calling balls when they should be strikes, more often than the reverse, then maybe, but I'm not aware of any studies showing that.

I agree this is most likely.

But, I will be interested to see how or if the challenge results skew less when it's a Veteran Pitcher vs Young Hitter as opposed to a Young Pitcher vs a Veteran Hitter.

[DJL44]

The delay is annoying. I think some batters might be using it as an additional timeout. They could speed it up a little.

 

[jctwins]

44 minutes ago, DJL44 said:

The delay is annoying. I think some batters might be using it as an additional timeout. They could speed it up a little.

 

There was a good discussion on Reddit about this. Apparently the players (when they were testing this) favored a challenge system over just letting the computer correct wrong calls immediately, which is what I'd think we as fans would like to see.

That said, I agree this could be done in 5 seconds without the graphic and advertisement. The theory I read in that discussion is that MLB wants the sponsorship on that graphic.

[amjgt]

55 minutes ago, DJL44 said:

The delay is annoying. I think some batters might be using it as an additional timeout. They could speed it up a little.

 

There is zero chance that teams let players treat challenges like this once games start to matter. 
Having those challenges is just too valuable to be wasting them as pseudo timeouts. 

[Parfigliano]

If Angel was still an ump behind the plate under this challenge system games would go forever.

[ashbury]

6 hours ago, amjgt said:

The argument I'd make against that point is that the person most equipped to consistently make correct challenge decision (the catcher) is on the side of the pitcher. 

I like that argument.  What I especially like is that it isn't symmetrical to the advantage that goes to the hitter in terms of offering at less-than-marginal pitches for fear of being rung up unfairly. 

Baseball is best when there is balance between things that aren't precisely mirror images.  The remarkable balance between a catcher throwing the ball to second base and a runner trying to get there on foot is another example.

[Jim H]

I have a question about the abs system. Is this right? The system converts the 3 dimensional strike zone to 2 dimensions. It is supposed to be centered in the middle of the plate. If I am right about that, my 2nd question is why are they centering it in the middle of the plate? Since most hitters actually hit the ball well in front of the plate, wouldn't it be fairer to center the zone at the front edge of the plate?

[jorgenswest]

I have been wondering about pitchers dood at locating with a lot of movement adjusting from the 3-D to 2-D strike zone. What about the pitchers that can throw the strike thats hit the front corner but is off the plate by the middle edge or that back door pitch that didn’t enter the strike zone until after the middle of the plate or the pitcher that hits the strike zone at the front of the plate but drops out by the middle? Will those movement and location skilled pitchers need to capture more of the plate and drop in effectiveness? Will they replaced by more pitchers with velocity? I hope not. Going 2-D will shrink the strike zone,

[Richie the Rally Goat]

On 3/5/2026 at 11:51 AM, Jim H said:

I have a question about the abs system. Is this right? The system converts the 3 dimensional strike zone to 2 dimensions. It is supposed to be centered in the middle of the plate. If I am right about that, my 2nd question is why are they centering it in the middle of the plate? Since most hitters actually hit the ball well in front of the plate, wouldn't it be fairer to center the zone at the front edge of the plate?

https://www.si.com/mlb/how-abs-challenge-system-works
 

Good question!

According to SI, you are correct, it is a 2D rectangular box at the middle of home plate the width of the plate and height adjusted to the player.

The article said that the robo-zone is slightly smaller than the average human-zone. My guess at the placement is for breaking balls. So the pitcher gets the back door slider, but can’t get the slider that breaks the front of the plate and away.

[Jim H]

Jorgensweet, I was wondering about that aspect of the abs system as well.  You might get more consistency in the strike zone from the abs system than a human, but by taking away the depth of strike zone you will likely penalize those pitchers with excellent command. I think it possible that the umpire will actually be right often but the abs system will over rule him. I suppose someday the system will be advanced enough to call strikes in 3D. Then everyone will have to adjust to that.