What Sinking ABS Challenge Rates Will Mean for Brewers

Early in spring training, as players were getting a feel for the ABS challenge system and the contours of the new zone created thereby, most teams—including the Brewers—allowed their hitters to challenge at will. The Crew ran out of challenges early in games more than once in the first fortnight of Cactus League games, which mildly exasperated manager Pat Murphy, but he waited until nearly the middle of the preseason schedule to crack down on the strategic approaches of players to the system.

As other teams have done the same thing, the global challenge rate has come down sharply. Early in the spring, hitters were challenging roughly 1 out of every 15 called strikes. For the last week, the average has been just under 1 in every 25 such pitches.

This was inevitable. Once everyone has a handle on the best usage of the system, it's important to learn when not to challenge a call that feels borderline. Game situation—relative score, count, base-out situation, inning, and whether or not the team has both of its challenges remaining—has to inform each choice about whether or not to challenge a call, rather than the batter's simple perception. Withholding some challenges to ensure that the team still has the right to mount one at a critical moment is part of every team's gameplan; it just wasn't part of most teams' early conversations during games that don't count.

Still, it's an important trend, because how often the league's batters challenge as a whole matters quite a bit to the Brewers. Though William Contreras has become synonymous with the catcher position for the Crew (and can hardly be optimized as a framer a second time), the team has a reputation over a decade old for improving the framing of catchers. They win at the margins of the strike zone, including by stealing some strikes on pitches that shouldn't be thus called. The ABS challenge system threatens that advantage, and the magnitude of value the Brewers are likely to lose is proportional to the frequency with which the league's batters tend to challenge calls.

The Brewers were eighth-best in baseball last year at getting called strikes when a batter took a pitch in the shadow zones, as defined by Statcast's Attack Zones model. It's important to know where they got most of those calls, though, because strikes can be stolen more safely if they're plucked from zones in which batters are less likely to challenge. Here's the heat map showing where the Brewers most often got those borderline strikes in 2025:

That's a pretty standard and stereotypical heat map. It's easier to frame pitches at the bottom of the zone than to do so at the top, but batters also swing more often at high pitches, anyway, so the pitch up there is usually thrown with the goal of getting a whiff or a weak fly ball, rather than in pursuit of a called strike. Those are supposed to come at the bottom of the zone.

For many of the same reasons, hitters challenge more often near the bottom of the zone than near the top—but not by as much as the heat map above might imply.

Hitters (and pitchers and catchers) are still getting accustomed to the new upper and lower bounds of the bespoke strike zones assigned to each batter, based on their height. The edges of the plate don't move, but what's high, what's low, and what hits the zone between those regions is newly defined—and still a bit of a mystery. The top of the zone seems to have come down a bit, but the bottom edge doesn't seem to have moved much for most batters. As a result, the Brewers might be able to hold onto some of their slightly out-of-zone called strikes for a while. Hitters will be wary of challenges on low pitches, where the success rate hasn't been very good and they're not as certain as they are about pitches inside and outside. Contreras needs to continue to excel at bringing up those pitches nipping at the knees of batters, but that shouldn't be a problem. In this way, fewer challenges might be good news for the Crew.

On the other hand, though, notice in that first chart that the challenge rate for catchers has been nearly flat throughout the spring. For the most patient team in baseball, that gives the Crew some concrete information. They should expect opposing catchers to challenge about 1 of every 50 pitches they take for a ball. That's why, so far this spring, they've experienced among the most sheer overturns against them, from both batters and catchers. They'll have to negotiate this aspect throughout the season; it might eventually need to dictate some minor changes in their approaches.

The Brewers play a specific brand of baseball, and can't afford to reorganize themselves every time the league tweaks a rule. That's for richer teams to do. The Crew needs to find ways to tailor their existing systems to new wrinkles, but never throw out those systems in favor of less efficient ones; that would be self-defeating. All spring, they've monitored these trends throughout the league, and they'll have to continue doing so—but it can't be the overriding consideration as they shape their plans to win games.