CHARLOTTE, N.C. — The pitch looked perfect. Thigh-high, 95 mph, right on the outside corner. Liam Hendriks was ready to celebrate a strikeout, and Roberto Alvarez was prepared to head back to the dugout, and then each was greeted with silence instead of a strike three call. Amid the quiet, one fan let his feelings be known. “Come on, blue, that’s a strike,” he yelled at home-plate umpire Cody Clark. And it was an eminently reasonable complaint, if not for one important fact.
It was a Thursday.
In Triple-A games this season, the day of the week matters. On Tuesdays through Thursdays, the strike zone is fully automatic, adjudicated by Major League Baseball’s automated ball-strike system (ABS), which tracks pitches using a dozen ultra-high-speed cameras and spits out the result into an earpiece worn by the home-plate umpire in less than half a second. Even though Hendriks’ fastball appeared to clip the edge of the zone on the digital rendering of the pitch seen in MLB’s app and on its website, ABS deemed it a ball — and the system, which the league says is accurate to less than 1/10th of an inch, is judge and jury.
The next day, as the Charlotte Knights again hosted the Durham Bulls, another borderline call. Charlotte catcher Evan Skoug snatched a low 1-1 pitch and froze his glove in the strike zone. Paul Clemons, the home-plate umpire, didn’t bite and called it a ball. Immediately, Skoug tapped his head — a motion that only mattered on Fridays through Sundays. Over the weekend, balls and strikes are judged by the umpires’ eyes, but players are allowed to challenge a call three times per game and retain their challenges if correct. During Skoug’s challenge, which from start to finish took less than 10 seconds, the scoreboard displayed a graphic of the pitch’s trail toward home plate, shown from the catcher’s perspective. As the pitch neared, the screen pivoted 180 degrees, to the pitcher’s perspective, to render the definitive judgment. The call stood. It was a ball, and it wasn’t particularly close.
Two varieties of the future of balls and strikes are playing out in Triple-A this season, and whether either wins out in the eyes of MLB will offer a fascinating insight into the league’s priorities going forward. The league’s faith in the ABS system’s fidelity and accuracy is clear. After nearly 20 years of tinkering, upgrading, testing, failing and repeating the process, the current incarnation of ABS is a technological marvel, its pieces and parts big league-ready. But installation at the major league level breeds a bevy of philosophical hesitations, all perfectly practical, each a sub-issue of the overarching question that continues to puzzle league officials and owners who aren’t quite sure of the answer.
Would robot umps really make baseball better?
The benefit of full ABS is simple: In a properly calibrated system, it completely eliminates human error. If technology exists to support a completely uniform strike zone — at Triple-A this year, the zone is the full width of the plate (17 inches), with the top set at 51% of a player’s height and the bottom at 27%, and is measured via a two-dimension plane set at the plate’s halfway depth point — then, the argument goes, why wouldn’t MLB seek perfection?
For the rejoinder, look no farther than Skoug, whose challenge was rejected in the Friday game in Charlotte.
“I’m completely against [full] ABS when I’m catching, because if you think about it, some of the best catchers that I’ve idolized and looked up to while playing have made their career defensively,” Skoug said. “It doesn’t really matter how great you hit if you can control the staff and steal some strikes. You can play for a really long time and you can make a lot of money.
“There’s so much more to the position value-wise that ABS would just put a damper on. But I think the challenge system is fun. I like watching hitters’ faces in the box. So it’s fun when the machine actually works and it shows you where the pitch was.”
It’s the point made by countless critics of robot umps: The art of framing a pitch — presenting a ball outside the zone so deftly that it tricks the umpire into calling a strike — is worth preserving. Not only for the advantages it can give teams with catchers who excel at it, but because turning a vital position into little more than hit-and-throw machines in the name of seeking ball-and-strike perfection is awfully cynical.
ABS challenge is compromise, an acknowledgment that, yes, some ball-and-strike calls are awful enough to warrant overturning, but umpiring by and large is good enough that a half-measure suffices. Further, as Skoug suggested, ABS challenge and its few seconds of drama offers tangible engagement for fans in the stadium who are always ready to cheer or boo, depending on the call.
“I personally like the challenge system better because catchers still have a job framing pitches, and I think it feels more real baseball rather than just a robot calling the strikes and balls,” said White Sox designated hitter Jake Burger, who was in Charlotte on a rehab assignment. “There’s a lot of benefits with it. Especially in big situations. [If] there’s a ball way off that’s called a strike three and you lose the chance to drive in a run, that’s where it comes into play. You can challenge it, and you feel good about that challenge.”
This has been an unintended benefit of the challenge system: ABS challenge introduces game theory that doesn’t exist with the full version. The point in the game matters: While only 1.8% of pitches in the first inning have been challenged this season, the number climbs in almost every inning, peaking at 4.9% of pitches in the ninth, according to MLB. Just as important is the count. The two most frequently challenged counts: 3-2 (9.6% of balls and strikes) and 2-2 (6.3%). “It’s more about letting the guys decide when they want to do it,” Durham manager Michael Johns said. “If you’re going to use it early, you need to be 100 percent. If it’s a 2-0 count and it’s the second inning and we’re up a few runs, have some common sense. Save them for the end of the game.”
But even then, more players than not will find themselves on the wrong side of the truth, like Skoug. In 91 games played with the challenge system during a Triple-A trial run last season, players challenged 518 pitches and were successful 48.5% of the time, according to MLB. Over the first 178 challenge games this season, teams used almost all of their head taps (5.4 per game) but calls were overturned even less frequently (44%). Considering that home-plate umpires graded out at 97.6% accurate last year — that includes a 2-inch buffer around the rulebook zone negotiated by umpires during collective-bargaining talks, which accounts for the difference between internal grades and those by independent auditors like Umpire Scorecards and Umpire Auditor, which suggest umpires get between 91% and 96% of ball-strike calls correct — perhaps the challenge failure rate shouldn’t come as a surprise.
“It shows you how good umpires are,” Johns said. “To start the year, we were 0 for 10 [on challenges]. And I said it to [his players]: ‘Every time you guys complain, think about that.'”
By no means is either system perfect. For all the fear of full ABS taking something away from the fabric of the game, ABS challenge comes with its drawbacks as well. Poorly used challenges open up the possibility of a blown call in a late-inning, high-leverage situation. Unique stances can muddle zones determined by a player’s height. Pitches don’t register, with one missing every 6.7 games, according to MLB. And at the major league level especially, where information can be relayed in real time from a dugout, there are concerns of players being alerted when and when not to challenge. While gaming the game may be baseball tradition, doing so with technology’s assistance would be antithetical to the anti-cheating rhetoric commissioner Rob Manfred preached in the wake of the Houston Astros scandal.
It’s enough to have kept MLB from diving headlong into a world governed by robot umps. Until recently, the technology and application had been substandard — including a previous version, used in the 2019 Arizona Fall League, that was laughably bad, with curveballs that clipped the bottom front of the zone hitting the plate and being called strikes. MLB scuttled that three-dimensional zone for 2D, upgraded to the Hawk-Eye system best known for its incredibly accurate line-calling in tennis and installed a dozen cameras calibrated to the fixed items on the field — home plate and the chalked baselines — that capture the flight of the ball at 330 frames per second.
Even with the proper tech, MLB is hoping ABS can be more. If the league is going to rubber stamp ABS of any variety, to upend a century and a half of history the same way it did with the pitch clock, the benefits must far outweigh the detriments. And watching the ABS system in action has brought a new potential benefit to the minds of a number of power brokers at the league and in ownership: Can ABS kill two birds with one zone?
For years, MLB has sought solutions to a rising strikeout rate that stunted the number of balls in play and slowed the game to a grind. The pitch clock took care of the speed-and-pace problems, but, thus far at least, the percentage of plate appearances that end in one of the three true outcomes — strikeout, walk or home run — remains at alarmingly high levels. This year, it’s 34.5%, which is marginally better than the record-setting 2019-21 seasons but still far higher than the recent past.
One way to counteract that would be with a newly defined strike zone — or even one called more closely to the zone in the rulebook now.
Though that zone is clearly defined — “The area over home plate from the midpoint between a batter’s shoulders and the top of the uniform pants — when the batter is in his stance and prepared to swing at a pitched ball — and a point just below the kneecap,” the official rendering, implemented in 1996, reads — it is not called that way. Letter-high pitches are balls today; the zone begins around the beltline, maybe the belly button for some, but no higher. Adjusting the strike zone would be nothing new for MLB. Since it first defined a strike in 1887, it has amended the zone in 1950, 1963, 1969, 1988 and 1996.
If MLB can conjure an ABS zone that brings the strikeout rate closer to 1983 (13.5%) or 1993 (15.1%) than 2013 (19.9%) or 2023 (22.7%), ABS is an inevitability. Doing so, of course, is easier said than done. For every solution that makes sense, there is a downside Encouraging pitchers to get away from their swing-and-miss-heavy, breaking-ball-loaded repertoires would do wonders, but to do so would necessitate incentivizing them to throw fastballs. That would require expanding the zone north and south, and high fastballs out of the current rulebook zone generate strikeouts even more than breaking balls, according to TruMedia.
Because the zone-as-agent-of-change idea has merit with the game’s heavy hitters, it is likely to follow a similar path to the pitch clock, which went through multiple versions and years of testing before being deemed ready for prime time. The A/B testing of full ABS and ABS challenge will give the league one data set, and it could return next season, whether at Triple-A or across the minor leagues, with a number of different zones to see if any has a demonstrable effect on strikeout rates and offensive production.
Even then, sources said, the debut of ABS in the big leagues is no inevitability — and seeing it in the major leagues in 2024, while not completely ruled out yet, is unlikely. MLB would need to get the umpires onboard, and while they don’t have veto power — their collective-bargaining agreement says MLB needs to prove the system is more accurate at calling balls and strikes than umps — their support for a system about which they’re deeply skeptical is imperative. Further, the league would need to convince owners that now is the proper time to implement the rule — to make another profound change to the game a year after introducing the pitch clock. Taking ABS to the league-and-union-run competition committee that vets new rules before testing any sort of strike-zone modifications would likely be premature.
“Before we discuss with the Joint Competition Committee whether to bring ABS to the big leagues, we need to settle on a strike zone and a format that improves the game for fans,” said Morgan Sword, MLB’s executive vice president of baseball operations. “We are using it across Triple-A this year in hopes of answering those questions with the help of players, coaches and umpires.”
Over the next four months, hundreds of thousands of pitches will be thrown at Triple-A — about half in the full ABS system and half in ABS challenge — and the data set will grow. Players will get savvier with their challenges and ideas for a new zone will germinate — could it be oval-shaped to get rid of tough-to-barrel pitches in the corners, one person wondered — and the strengths and weaknesses of both ABS systems will reveal themselves. And that very basic binary — ball or strike? — will remain, at least for now, as it has for a century and a half: perpetually in question.