We're about to kick off our first postseason under the new era of ABS challenges. So we want to give you a quick primer of what to expect.
In October, every ball or strike challenge is going to be magnified, especially if they swing a playoff game or two or three.
With the Wild Card Series about to begin, let's take a look at each of the four series -- which teams are the best at challenging, which players you might see challenge in a big moment and so on.
Here are the ABS storylines to watch in the Wild Card round.
PHILLIES AT BRAVES
1) The Phillies are the best team in baseball at overturning calls
The Phillies rank No. 1 in MLB by a wide margin in "Overturns vs. Expected," which tells you how many calls they've successfully overturned compared to what you'd expect from the average team seeing the exact same pitches. Phillies batters are the second-best at overturning calls while at the plate, and their catchers are the best at overturning calls behind the plate.
2) Bryce Harper never met a challenge he didn't like
Harper sees precious few pitches in the strike zone as it is. He doesn't want to let them go by -- so if a strike gets called against him that he doesn't think should be, he's challenging. Harper is one of the most aggressive challengers in the Majors, pulling the trigger on 17% of the pitches he's allowed to challenge. He doesn't win all the time -- he's 21-for-47 on challenges -- but he wins on volume. Those 21 successful challenges are second most of any hitter.
3) J.T. Realmuto wins almost all his challenges -- but he could challenge more
Of the 77 catchers who challenged at least 20 calls this season, no one won a higher percentage of them than Realmuto. The Phillies backstop went a ridiculous 70-16 on his challenges, a win rate of 81%. That's great -- but it also means Realmuto should be more aggressive. He only challenges about a quarter of the incorrect calls that go against the Phillies, which means he leaves more winnable challenges on the table than nearly any other catcher.
4) Sean Murphy is great at not leaving challenges on the table
The Braves catcher, on the other hand, is always willing to challenge a close call, even at the risk of being wrong sometimes. He's correctly challenged over half his winnable opportunities, one of the highest rates in the Majors. Murphy doesn't win as often as Realmuto -- he's at a 60% win rate for the season -- but Braves pitchers can be confident that, if there's a call that might go their way, Murphy is going to be aggressive on their behalf.
PADRES AT CUBS
1) The Cubs win challenges the most often of any playoff team
Chicago has won 59% of its challenges this season, a top-five mark in the Majors and the best of any 2026 playoff team. The Cubs are also the second-best team after the Phillies when it comes to Overturns vs. Expected, with good success by both their batters and catchers.
Carson Kelly is a Realmuto Lite at catcher (a great 69% win rate on challenges, but not as aggressive as he could be), while the disciplined Seiya Suzuki (12-5 on challenges) and Alex Bregman (15 challenges won) are among Chicago's best hitters.
2) The Padres are not-so-great at challenging
San Diego, on the other hand, only wins half of its challenges, which is low. Padres batters have won 45% of their challenges, and their catchers have won 54% -- both of those marks rank sixth lowest of any team.
Manny Machado is the biggest culprit at the plate. He's challenged a lot of calls this season, but he has not won a lot of challenges. Machado is 10-for-28 on challenges. Of the 67 hitters who've challenged at least 20 times, his 36% win rate is bottom-10.
Twenty-year-old star prospect Ethan Salas will be interesting to watch if he catches any games in this series. Salas has only been in the big leagues for a month, but he's done a good job being aggressive and capitalizing on winnable challenges.
WHITE SOX AT ASTROS
1) Jose Altuve is aggressive AND good
Altuve, who has a small strike zone, has challenged 37 calls this season, third most of any hitter. And he's smart with his aggressiveness. Altuve still wins 57% of his challenges even while challenging a lot. His 21 wins are tied for second most with Harper, and he got there on 10 fewer challenges. Altuve has taken six strikeouts off the board against him, which is a lot. He makes those challenges count.
2) Murakami is aggressive but not as good
Munetaka Murakami isn't afraid to challenge calls, either, especially because selectivity at the plate is such a big part of his game. He's challenged 34 calls this season, almost as many as Altuve, but he hasn't had quite as much success. Mune has a 16-18 record on challenges, but those challenges won give him more chances to zero in on a pitch to mash over the fence.
3) White Sox catchers are the worst at flipping calls, but they always use their challenges
White Sox catchers challenged more calls, 280, than any team in the regular season. But they won only 49% of those challenges, the lowest win rate of any team. League-wide, the fielding team wins challenges 58% of the time. The White Sox lost 142 challenges this season, almost 30 more than the next-closest team, the Brewers. Then again, their 138 challenges won was fourth most of any team. They leave the fewest challenges on the table; sometimes that's good.
RED SOX AT YANKEES
1) Yankees hitters get a lot of value out of their challenges
The Yankees are an aggressive challenging team when they're at the plate, and that aggressiveness has paid off overall. Their hitters have won 96 challenges this season, tied with the Mets for the most of any team offense, and they keep up a challenge win rate over 50%. One name to watch here: George Lombard Jr. The Yanks' rookie shortstop is 7-for-9 on challenges already, and he's not afraid to pull the trigger.
2) Judge doesn't challenge a lot, but he does win
If Aaron Judge plays in this series, don't expect a ton of challenges from him, even though his 6-foot-7 frame gives him a strike zone umpires don't see every day. Judge doesn't like to challenge a lot, but when he does, he usually knows what he's doing. He went 6-for-8 on ABS challenges this year -- all of those on pitches at the bottom of the strike zone.
3) Adley wins a ton as a catcher
The Red Sox big-ticket Trade Deadline acquisition, Adley Rutschman, can have as much impact on a game defensively as he can offensively. That extends to challenging calls. Rutschman is 46-22 on challenges this season, a 68% win rate -- and he's 24-10 (71%) since he got to Boston. Red Sox catchers have been very good at creating strikeouts via successful challenges -- their 43 "K flips" are third most of any team, and most of any playoff team -- and Rutschman is now a big part of that.