What Will ABS Actually Change in Baseball?
Automated Ball-Strike Challenges will be in MLB in 2026, so how will or won't teams use their challenges?
In 2026, MLB will implement the ABS (Automated Ball-Strike) Challenge System, allowing players to challenge the umpires’ ball and strike calls. Teams will need to be careful about using these challenges though, as after two failed challenges, they’ll run out for the rest of the game.
The larger baseball community is speculating on how teams may encourage or restrict usage of these previous challenges, but since it’s a brand new system, there is far from any consensus on the matter. At large, predicting the discrete outcomes of ABS is an impossible task, but I wanted to give my thoughts on what I think may or may not happen. I’ve split this article up into three sections, with each my more controversial take of each group going second (and being marked with a *)
Section 1 - What I think WON’T Happen
The value of framing won’t die
Framing has long been an underrated but controversial skill in baseball, mostly because it’s all about tricking the umpires into making wrong calls. While it is very possible that we may never see a defensive season as valuable as Patrick Bailey’s recent performances, framing won’t completely die out either.
What people are missing in predicting the total downfall of framing is that good framers can still deter pitches from being challenged. As mentioned by sluggers Brent Rooker and Vinnie Pasquantino on Effectively Wild, there may be times where a hitter thought a pitch was wrongly called a strike, but then they may look at the catcher’s framing of the ball and get tricked out of their instinct. Also, these challenges aren’t unlimited, so good framing catchers will still steal a ton of strikes over the course of a full season.
Experienced players won’t dominate the challenge system*
This is possibly my biggest ‘zag’ of this whole article, as it’s assumed that veterans will get the lion’s share of a team’s challenges due to their experience and status. We even see this idea in other sports, where many NBA stars (like Jaylen Brown) will complain about younger players who draw lots of fouls, citing that favorable whistles should be reserved for older players.
But I think that the younger players, growing up and learning the game with more strike zone data, will prove to be good judges of the zone when at bat. I don’t think that the age and experience of a batter will determine their success rate when challenging, though for catchers and pitchers that may very well be the case.
Section 2 - What I think MIGHT Happen
Teams will determine which pitch types to challenge
Players have had blind spots regarding certain pitches for as long as the curveball has existed, as shown by their higher chase rates outside of the strike zone on certain pitch types. Due to these blind spots, players may erroneously challenge at a higher rate on breaking balls than fastballs. It makes sense logically, as fastballs are less likely to have enough movement to look like balls while being strikes than breaking pitches.
What I’m less certain about is the types of pitches that teams will challenge more frequently within the umbrellas of fastball and breaking ball. For example, I have zero idea if sliders, curveballs, changeups, or the emerging splitters will be challenged at higher rates. I imagine that due to off-speed being more frequently thrown on two-strike higher leverage counts, they may see inflated challenge numbers relative to what they should, even after teams adjust for the lower probability of a successful challenge. What I do know is that teams should pay close attention to which pitch types are better to challenge and hitters should challenge accordingly.
Teams will begin to optimize which pitch locations to challenge*
This is a similar take to my previous one, but a little less intuitive. While pitch types look the same to every hitter, location will always appear different, due to head placement and batting stance. With that said, hitters can still isolate where they think a pitched miss, whether that be up, down, inside (closer to the hitter), or outside (away from the hitter). Some hitters have different senses of the zone, and we know that because some hitters chase in different directions than others. In high school, I definitely had a worse sense of inside pitches, so I’m definitely familiar with this.
One hitter who may reflect this mindset is the best in baseball, Aaron Judge. He had the eighth-most wrongly called strikes against him among hitters who saw 2500+ pitches in 2025, many of which were lower pitches. For one of baseball’s tallest hitters (at 6’7), he may be instructed to consider his stature when making challenge decisions, and will likely benefit from challenging lower pitches more than other players.
Section 3 - What I think WILL Happen
Teams will filter for high-leverage situations
This one is incredibly obvious, but it feels important to say anyways. I’m certain that sometime this season, there will be an egregious miss on an 0-0 count with nobody on base that doesn’t get challenged. Fans will be livid, but teams won’t allow players to challenge in those situations just because the reward for a successful challenge is so low. Risking losing a challenge, on a pure expected value basis, will almost always be a net negative in these low leverage situations. On the other hand, I’m sure that ninth innings, full counts, and runners-on situations will feature increased challenge rates.
What is more unknown to me is what leverage cutoff may exist for teams. For example, if there’s a 3-0 count with two out and nobody on base, will a player challenge a strike call? If they win, they get the base, but it may not matter if they can draw a walk from a still-favorable 3-1 count. There’s a lot to consider, and I imagine that teams will care about expected run probability, but I don’t know how dire an inning has to get before they ban players from challenging altogether.
*Note: The overall percentage of pitches challenged will increase into counts, but the percentage of challenges used on later pitches won’t stand out as much due to early counts being a larger proportion of all pitches (every at-bat sees a first pitch pitch, not all see a sixth).*
Pitchers will be the losers of the challenge system*
This may seem crazy, as it’s very bold to say that the player with the clearest view of the zone as interpreted by the machines verifying challenges will be the least effective at judging the zone. However, I do anticipate pitchers to struggle more with challenging than anticipated, mostly due to being victims of framing themselves. Also, it’s difficult to judge if a ball went through an arbitrary square when you’re >50 feet away, even if you’re looking at it.
The other variable at play here is that the majority of incorrect calls are should-be balls called as strikes, meaning that at more points in the game, a hitter challenge would succeed. I suppose an even bolder prediction would be that we’ll see pitcher-initiated challenges fade throughout the year (or few years), but that requires knowing the initial rate at which pitchers will be initiating challenges, which is an impossible prediction to make.
I look forward to going back to this article in 2027, analyzing the stats, and seeing where I went right or wrong here.