With the World Series beginning tonight, all eyes are on baseball. While the Milwaukee Brewers and Tampa Bay Rays have certainly had impressive seasons, the real star of the game has been the rookie Automated Ball-Strike (ABS) Challenge System that’s used to help mediate balls and strikes. It operates on a secure network developed by Major League Baseball (MLB) with T-Mobile. Most fans love it, as do the players I’ve spoken to about it.
It’s officially transformed baseball from a game of potential human error into a high-stakes, high-tech game of poker. The numbers tell a fascinating story about who holds the cards, when they bluff, and how October baseball has turned up the volume on digital appeals.
During the regular season, according to MLB, the ABS quietly established its rhythm. Teams challenged an average of 4.4 pitches per game, or roughly 2.2 challenges per team, with human eyes proving far from perfect as players walked away with a 53.9% overturn rate. By the playoffs, the safety net shrank and the stakes skyrocketed. Through the end of the National and American League Championship Series, challenge usage climbed slightly to 4.6 pitches per game, and accuracy surged to a 60.5% overturn rate. When every single pitch can define a season, players stop guessing and start calling out genuine mistakes with surgical precision.
But players aren’t challenging the first pitch they dislike. The ABS challenge is a limited resource, and teams covet it like gold. Early on in games, from the 1st through the 3rd innings, players initiated only 28.6% of all challenges as managers and players hoarded their two allotted appeals. By the 7th inning and beyond, those stored challenges came out of the vault to account for 39.1% of all reviews.
The raw volume of challenges across different counts can be equally deceiving. The majority of regular-season challenges, 59.6% occurred in 0-0 counts, which sounds high until you realize 0-0 is the most frequent count in baseball. In reality, players challenged a tiny 2% of all 0-0 pitches. The true battles occurred on edge-case counts where a single call alters an entire at-bat. On 3-2 counts, players challenged 9.3% of all pitches, representing the highest challenge rate of any count. More broadly, 6.2% of all three-ball pitches were challenged compared to 4% of two-strike pitches. A missed call on 0-0 is an annoyance, but a missed call on a full count is the difference between a game-changing walk and an inning-ending strikeout.
Comparing how tonight’s teams navigated the system reveals starkly different strategies. The Brewers adopted an aggressive, fire-at-will approach. After averaging 2.4 challenges per game in the regular season (8th most in MLB) with a 52.8% overturn rate, Milwaukee ramped up to 3.4 challenges per game in the postseason so far while improving its success rate to 59.2%. The Brewers used the system as an offensive weapon, putting relentless pressure on the opposition.
The Rays went in the opposite direction. After averaging 2.1 challenges per game in the regular season (13th in MLB) with a matching 52.8% overturn rate, they dialed back to a disciplined 1.4 challenges per game in the playoffs. Their reward for extreme restraint was a staggering 69% overturn rate. They rarely challenged, but when they did, the robo-ump almost always agreed.
Interestingly, during the regular season, catchers initiated 53% of all challenges, batters accounted for 45%, and pitchers managed 2%. Pitchers, watching from 60 feet and 6 inches away through a wall of bodies, simply lack the visual angle to contest borderline pitch locations. Brewers star pitcher Jacob Misiorowski told me this summer that he completely trusts his catcher to challenge, and I feel most pitchers agree. And with good reason: In the postseason, catchers have cemented their status as masters of the strike zone by initiating 61% of all challenges, while batter usage dropped to 39% and pitchers initiated just one challenge. Equipped with a squatted view right behind the glove, modern catchers are no longer just framing pitches but acting as real-time judges, deciding in a fraction of a second whether to trust the umpire’s call or overrule it with a flick of their wrist.
ABS has added incredible drama to games. And I expect in the World Series, the timeliness and importance of each call may be crucial to which team will win its first-ever Fall Classic title.
This article was originally published on Forbes.com