MESA, Ariz. — For the first five months of Triple-A Iowa’s 2025 season, right-hander Gavin Hollowell let his catchers decide whether to signal for the Automated Ball-Strike challenge system on any pitches he threw. At the end of the year, Hollowell figured he’d take a shot at using the ABS on a called ball he thought appeared to be a strike. Related Articles New MLB union head Bruce Meyer dismisses salary cap and defends free agency and arbitration as labor clash looms Photos: An inside look at Chicago Cubs spring training Chicago Cubs notes from camp: Kevin Alcántara puts injury behind him — and a lockout ‘all but guaranteed’ Bruce Meyer elevated to MLBPA interim executive director after Tony Clark’s forced resignation Chicago Cubs top pitching prospect Jaxon Wiggins is learning in his first taste of big-league camp “And I was wrong, so I won’t be challenging anymore,” Hollowell told the Tribune with a laugh. Major League Baseball is implementing the ABS challenge system for the first time in the regular season after testing it during spring training games last year and utilizing it in Triple A since the 2023 season. Most of the Chicago Cubs’ projected opening-day roster doesn’t have experience with it, beyond some exposure during Cactus League games in 2025. And even that was limited to spring training ballparks that had the required Hawk-Eye data available to check ball-strike calls in real time. For the Cubs, that meant they could test it only in select road games; Sloan Park was among the Cactus League parks without available Hawk-Eye and Statcast data. The Cubs also had more home games last spring because of their trip to Japan for the Tokyo Series, so some players, such as left fielder Ian Happ, never played in an exhibition game that had the ABS system available to test. “I’ve never seen it in action,” Happ said. “It’s going to be important throughout spring to get a look at it and challenge. You’ve got to see what it feels like, you’ve got to get your bearings on your eyes. … It’s a new system for all of us. I think the league will adapt, similar to pitch clock and everything. It’ll be a quick transition.” The Cubs plan to have discussions throughout spring training on strategies for when to best deploy their ABS challenges in regular-season games. Manager Craig Counsell expects to hold a meeting at the end of spring training to create some structure around their ABS usage. He’s most worried about the disputes that could arise: Was the challenge requested in time? Did the umpire not allow a team to challenge but OK’d a similar challenge attempt by the other team? “Players are going to get this wrong, and we’re going to get: Why didn’t we challenge?” Counsell said. “There’s going to be some of that. Maybe we’ll find out it’s pretty hard to be an umpire — I think that’s probably what we’ll find out.” MLB data shows the ABS adds about one minute per game, estimating 15 seconds for every challenge. The key rules for this season: Challenges can be initiated only by the pitcher, hitter or catcher with a double tap on their head within two seconds of the umpire’s call. If the umpire believes a challenge call was influenced by help from someone else, the request can be rejected. Each team receives two challenges for a nine-inning game, with a team getting to keep its challenge if the call is successfully overturned. If a game goes to extra innings, a team will receive one challenge to use if it had none entering the extra inning, a process that repeats for each extra inning played. Umpires have discretion to return a baserunner to a base if a pitch and challenge affects a play. Challenges are not allowed if a position player is pitching. Any part of the baseball touching the strike-zone box results in a strike MLB is instituting safeguards to curb cheating with the system. Pitch location data, like on MLB’s Gameday app, will be delayed by roughly five seconds. Teams are prohibited from having their own ball tracking systems in their ballparks, so the only pitch data from major-league games will come from Hawk-Eye. A process will be in place for MLB to review all challenges to ensure there is no evidence of anything underhanded. In Triple A last season, games averaged 4.2 challenges with a 50% overturn rate, similar to the figures from 2025 spring training, when there were 4.1 challenges per game and a 52% overturn rate. The ABS strike zone features a 17-inch width, and the height will be based on the hitter’s size. Every player will get a verified measurement at spring training to set the top and bottom of the zone. The Automated Ball-Strike system is displayed on a screen behind the outfield during Cubs spring training at Sloan Park on Tuesday, Feb. 17, 2026, in Mesa, Ariz. (Armando L. Sanchez/Chicago Tribune) Cubs pitching coach Tommy Hottovy believes some pitchers could benefit from the more square shape of the ABS zone and get more clipped strikes in the corners. “That’s something we might try to play around with and see if we can take advantage of more of those type of pitches,” Hottovy said. “You have an understanding of how you think it’s going to work, but a lot of it’s just read, react. How did that work? What can we do differently? And make those adjustments.” Understanding the zone and how balls in the corners could become more frequent strikes is part of the Cubs’ spring process to get comfortable with the ABS system. Catcher Carson Kelly said the Cubs have talked about ways to train by receiving pitches off of a machine to test catching balls on the edge and making pseudo challenges in the practice setting to see if their eyes are reading the zone correctly. “It’s an exciting addition to the game, but also it can come down to being very important,” Kelly told the Tribune. “I think it’s going to be very apparent when those big moments are happening and there’s a big pitch that needs to be made, if they execute or if it’s just off, it’s worth the challenge.” The Cubs tested out the ABS system this week at Sloan Park, incorporating the full graphics reveal on the video board for each challenge. Players weren’t restricted by how many times they could challenge during a live batting practice at-bat, like they will be in the regular season, because the Cubs want their veteran players to get comfortable using it. At one point from behind the plate, catcher Miguel Amaya challenged a Colin Rea pitch that was called a ball. The ABS replay confirmed the pitch was outside the zone — by 0.3 inches. “I like the old school, let the umpire do his job kind of thing, but it’s exact,” Hollowell said of the ABS. “It sometimes feels like you’re throwing into a shoebox, feels a little small, but we know it’s probably accurate. I enjoy it from the accuracy standpoint.” ...read more read less