Next season, umpires will continue to make ball-strike calls. A challenge system will be added. Pitchers, catchers, and batters will be allowed to challenge ball-strike calls. Each review will take about 15 seconds. In each game, each team will be allowed to challenge until they accumulate two upheld calls.<\/p>\n
In the last ten years, baseball has made many changes to improve the game.<\/p>\n
\u201cTo start the 2014 season they had this new thing called instant replay. I can\u2019t imagine the game without it today. I think we\u2019ll say the same thing with all the rule changes and all the things they\u2019re trying to do to make this game as clean and as natural as possible. With new technology and the things that can get it right, I think players are for it, for sure. As I am.\u201d \u2014 Torey Lovullo<\/a><\/p>\n In 2023 and 2024, in the minor leagues an automated system for calling balls and strikes was experimented with. Possibly because of the need to make decisions about the strike zone, it was decided to proceed with only a challenge system.<\/p>\n \u201cTriple-A ballparks used ABS this year for the second straight season, but there is little desire to call the strike zone as the cube defined in the rule book<\/a> and MLB has experimented with modifications during minor league testing.\u201d \u2014 Ronald Blum, November 2024<\/a><\/p>\n The Joint Competition Committee (JCC).<\/p>\n \u201cZac Gallen is on the Competition Committee (comprised of six owners, four players and one umpire) and heard first-hand on a call Tuesday morning that baseball is moving forward with another significant change.\u201d \u2014 Alex Weiner<\/a><\/p>\n The JCC approved the Challenge System 9-2. Also, baseball teams approved the Challenge System 23-7.<\/p>\n \u201cUSA Today\u2019s Bob Nightengale reported that 23 of 30 clubs voted in favor of the change, along with all six owners [in the competition committee]. Gallen said based on the results, the players submitted three yes votes and one no. The umpire voted against the measure.\u201d \u2014 Alex Weiner<\/a><\/p>\n The Challenge System was used successfully in spring training.<\/p>\n \u201cDuring Spring Training, a challenge system was used not unlike the one already utilized in the majors for instant replay on the bases. Each team started the game with two challenges available to them, and would retain their challenge after using it successfully or lose it after using it incorrectly. As noted by Ronald Blum of the Associated Press<\/a> just before Opening Day, teams challenged 2.6% of called pitches during the spring with just over four challenges per game and a success rate of 52.2% overall. If those numbers were to hold, that would mean the ABS challenge system overturns just two ball-strike calls in the average regular season game.\u201d \u2014 Nick Deeds, MLBTR<\/a><\/p>\n \u201cI think the fans are gonna love it. I think it\u2019s gonna add a new dimension to the game that fans really get into, just because there\u2019s tension and excitement when someone challenges and you see it on the board.\u201d \u2014 Tim Tawa<\/a><\/p>\n Several visualizations of the strike zone exist. Strike zones visualizations range from the zone in each umpire\u2019s head, to the Umpire Scorecard Estimated Umpire Zone (EUZ) (it differs for each umpire and each game), to the broadcast zone (it has flaws), to the official zone. The Challenge System will include it\u2019s own visualization. Although it may be closest to official zone, it was said that the challenge zone may differ slightly at each venue.<\/p>\n \u201cWhat any individual thinks of as the strike zone is unlikely to be perfectly identical to the zone used in ABS, and that\u2019s supported by the fact that nearly half of challenges made to umpire calls wound up being incorrect. That suggests players aren\u2019t always more in tune with what the true strike zone looks like than umpires are, and a move to fully automated ball-strike calls could be a jarring adjustment for both pitchers and hitters as they adapt to a more accurate but wildly unfamiliar strike zone.\u201d \u2014 Nick Deeds MLBTR<\/a><\/p>\n \u201cI like it [The Challenge System] better than just a fully automated zone because it still allows for catcher\u2019s framing to a certain degree. But the biggest issue for me right now is… there\u2019s about four different strike zones that are being used to be judged.\u201d \u2014 James McCann<\/a><\/p>\n \u201cConsistency metrics provided by @UmpScorecards represent the proportion of taken pitches considered consistent with the umpire\u2019s established zone in any given game. Our algorithm begins by finding the \u2018established\u2019 zone, or what we call the Estimated Umpire Zone (EUZ).\u201d \u2014 Explainer at Ump Scorecards<\/a><\/p>\n \u201dIt\u2019s setting the people within the game up for failure. Because catchers are getting graded one way, umpires are getting graded another way. They\u2019re getting mad at each other because the strike zones are somewhat different.\u201d \u2014 James McCann<\/a><\/p>\n \u201cAnd then you\u2019ve got a whole other group of people that are seeing the broadcast strike zone, which isn\u2019t the same strike zone as what we\u2019re getting graded on. So I say all that introducing the ABS challenge system is going to basically make one strike zone. … It\u2019s going to standardize it.\u201d \u2014 James McCann<\/a><\/p>\n \u201cWhat worries me is the ABS zone varying from stadium to stadium. I guess that leads to a little bit of home field advantage, knowing that the strike zone plays a little higher, a little lower, a little more of the first base side, the third base side, whatever it may be.\u201d \u2014 James McCann<\/a><\/p>\n \u201cI was just curious what the shape of the strike zone was gonna look like from a digital standpoint. I just wanna make sure that the heights of the players are strictly enforced. I know in Triple-A, not all the heights were necessarily exact.\u201d \u2014 Zac Gallen<\/a><\/p>\n In addition to whether the call was likely wrong, a few other considerations are the umpire behind the plate, the potential impact on run expectancy, and the impact on win probability. When all the considerations are aligned (for example umpire with 9% inconsistent calls, count is 3-2 with bases loaded, and a 1-point game), they can point to plate appearances that call for aggressive challenges.<\/p>\n Types of Umpires. I looked at the consistency in umpire calls compared with the Estimated Umpire Zone (EUZ) (for that game and that umpire). After looking at some of the umpires that called Diamondbacks games<\/a>, there are different types of umpires:<\/p>\n Consistent calls at one level: great, average, and poor. An example is Derek Thomas who had very low inconsistency rates of 1.8% and 3%. Looking at the Umpire Scorecard Website, for consistent umpires the Diamondbacks can do a pre-game adjustment of the aggressiveness of their challenges.Inconsistent calls (sometimes great, sometimes average, and sometimes poor). An example is Tripp Gibson who had inconsistency rates of 1.4%, 5.3%, and 9% in Diamondbacks games. When an inconsistent umpire calls the game, the Diamondbacks can monitor the game and decide whether to adjust the aggressiveness of their calls for that game.<\/p>\n Run Expectancy (RE24). The possible impact of a challenge was determined by the 2024 run expectancy table in this FanGraphs article<\/a>.<\/p>\n The following situations can be challenged with a large RE24 impact.<\/p>\n When bases are loaded, challenging a strike (hoping for ball four) or challenging a ball (hoping for a strikeout) could impact RE24 by at least .71 runs.With runners on first and third base, with zero or one outs, challenging a ball (hoping for a strikeout) could impact RE24 by at least .69 runs. With runners on first and second base, with zero or one outs, challenging a strike (hoping for a walk) could impact RE24 by at least .68 runs.With a runner on first, with zero outs, challenging a strike (hoping for a walk) could impact RE24 by .60 runs.With a runner on third base, with one out, challenging a ball (hoping for a strikeout) could impact RE24 by .60 runs.<\/p>\n When the two teams are tied or within 1 run, the impact of a successful challenge could have a significant impact on win probability. If the game is close, it becomes very important that challenge opportunities are not lost. Another situation would be when the Diamondbacks are several runs behind. Because of their above average offense, the Diamondbacks can unexpectedly score a lot of runs. For that reason, challenge opportunities should be captured, even when the team is far behind.<\/p>\n \u201cGuys aren\u2019t just gonna be challenging left and right. There\u2019s some gamesmanship to it. Early in the game, two outs, nobody on, challenging a borderline pitch and getting it wrong costs your team a valuable challenge down the road. I think that\u2019s gonna be interesting to see how different teams operate.\u201d \u2014 James McCann<\/a><\/p>\n The Challenge System Favors Pitchers.<\/p>\n A perspective that is shared by Torey Lovullo and Andrew Saalfrank is that The Challenge System will shrink the strike zone. Overall, it will benefit batters. Will the smaller strike zone (instead of the larger one used in past seasons) mean that most successful challenges are by batters? My view is that the answer will depend on what run expectancy situations happen and it will depend on which umpire is calling balls and strikes.<\/p>\n \u201cFrom a hitter\u2019s standpoint, my generation, I feel like the pitchers had an advantage. They were getting balls off the edges of the plate. Now the balls are having to be put on the plate. I think that\u2019s the way this rule should be.\u201d \u2014 Torey Lovullo<\/a><\/p>\n \u201c[As a pitcher], I think you benefit from not having it [The Challenge System], just getting those calls off the corners. I think it\u2019s going to make pitching a little bit more difficult in terms of ERAs and stuff like that are going to have a whole different viewpoint to them. Statistically, I think it\u2019s going to have a big impact on the game, just because it shrinks the small-ish zone even more for the hitters that are paid to do what they\u2019re doing.\u201d \u2014 Andrew Saalfrank<\/a><\/p>\n The Challenge System could favor the Diamondbacks in 1-run games.<\/p>\n