Scott Servais, now manager of the Seattle Mariners but a catcher during his playing career, remembers when a member of the front office explained to him just how valuable catchers can be in tipping a game in their team’s favor.

“One of our analysts told me, ‘Scott, if we get two 3-2 pitches in the course of the game, that can mean up to half of a run,’” he said recently.

He was referring to the value of pitch framing — “stealing” a strike via the catcher’s expert sleight of glove. Half of a run for just a couple of extra strikes.

“That’s huge,” Servais said. Even for someone who intuitively understood the defensive contributions of catchers, it was striking.

Servais played during the Mike Piazza era, when the Hall of Fame slugger ushered in an appreciation and expectation for catchers’ offensive production. Catching has always been a uniquely demanding position, but backstops at the time were seen primarily as another spot in the lineup from which to generate runs.

Then, around 2008, with the addition of PITCHf/x in major-league ballparks, teams started to quantify stolen strikes. Pitch framing became part of how catchers are trained and evaluated; coaches started to teach it, and players who couldn’t learn the skill were largely phased out.

In the decade-plus since, the defensive demands on catchers have only grown. Pitchers throw harder than ever, teams cycle through more pitchers per game, and scouting reports are ever more detailed. The running game has slowed — though if all goes according to MLB’s plan, that tide could turn starting next season — but on the whole, “the job of the catcher has never been more difficult,” said Tanner Swanson, the New York Yankees catching coordinator.

“And yet catchers are performing at a really, really high level,” he said.

“It's not so much on the legs anymore,” Phillies manager and former catcher Rob Thomson said. “But mentally, it’ll wear on you.”

It all amounts to MLB teams prioritizing strong defense from their catchers. The 2022 Houston Astros won 106 games and the World Series with Martín Maldonado — OPS+ of 69 — catching 113 in the regular season and all but two in the postseason and generally being considered a cornerstone of the club. Jose Trevino, baseball’s best pitch framer last year, was a 3.1 fWAR player — more than Luis Arráez, Matt Olson or Kyle Schwarber — despite below-average offense.

After all, preventing runs is just as valuable as creating them. Consider that last season, the league-wide OPS on a 2-1 count was .908 and on a 1-2 count, it dropped to .414. Even with the pitcher doing most of the work, every single pitch of a game presents an opportunity for the catcher’s defense to tilt the scale one way or the other.

But that could all change very soon. So-called robo-umps loom, and as they creep closer to the big leagues, it’s becoming impossible to ignore that baseball is at an inflection point for catchers. Some form of the automated ball-strike system is coming, and the position will have to adapt.

“It's gonna change the game more than anything else in our lifetime,” Servais said.

The inevitability of ABS

In 2019, robo-umps debuted in the Atlantic League. The independent league partnered with MLB, allowing it to serve as a testing ground for more extreme or preliminary experimental rules. While the effect wasn’t much to look at — a human umpire still stood behind home plate and signaled the calls relayed to him by a computerized eye-in-the-sky — it represented a seismic shift on the distant horizon.

Since then, the automated ball-strike system (ABS) has made its way into and up through affiliated ball. Last season, a handful of the Triple-A stadiums featured ABS, exposing prospects on the cusp and rehabbing major-leaguers to the system.

At the same time, a Low-A league and the Arizona Fall League introduced a riff on robo-umps: a ball-strike challenge system. Human umpires called the game, but hitters, catchers and pitchers (and no one else) could challenge calls, which were then deferred to the computer. Each team started the game with three challenges, with successful challenges retained.

The sense, supported by commissioner Rob Manfred’s public comments, is that ABS at the major-league level is an inevitability. But to change something so fundamental and so ubiquitous in the game, the technology has to be fail-proof and the consequences thoroughly accounted for.

And so, at the winter meetings in December, Manfred hedged when asked about the timeline. “The one thing I will say from a developmental perspective: We learned a lot about ABS in 2022, suggesting to me that we are probably not done learning about ABS,” he said.

Accordingly, the experiments are set to expand significantly in 2023. Next season, all 30 Triple-A stadiums will feature ABS, and each will split time between full ABS and the challenge system.

The league sees a couple of benefits to the challenge system. From a procedural standpoint, ramping up from there to full ABS would be easier than rolling back total implementation. And at a time when the primary goal of most rule changes is to enhance entertainment value, the strategic intrigue of navigating the allotted appeals is an added perk.

Either way, the role of receiving in a catcher’s job description is poised to change drastically in the next couple of years. Not knowing exactly when or how that shift is coming makes it difficult for catching coordinators to adapt in advance.

What they do know, however, is that they’re not happy about what they fear is the future of catching.

What it means for catcher development

Tucker Frawley, the Minnesota Twins catching coordinator, spends some time in the offseason ensuring that the team’s training systems are “in line with how we see big leaguers actually earning those paychecks.”

His job is to give the organization’s minor-league catchers the best chance to succeed and contribute at the major-league level. Personally, he has a lot of appreciation for the mental side of catching — the ability to digest the huge amounts of information available and turn them into effective game-calling — but that can be tricky to measure.

And so instead, “I've been locking in lately on the receiving side,” Frawley said. “Because it's the most easily quantifiable.”

Swanson agreed: “I think teams have gotten smarter and better at figuring out how to optimize that skill and not just try to acquire it.”

Swanson, in fact, was at the forefront of the “knee-down” setup that swept baseball in recent seasons, as teams realized the stance put catchers in better position to steal strikes. There had been a stigma attached to what was once considered an unathletic approach, but when Mitch Garver went from one of baseball’s worst pitch framers to among the best in a single offseason of working with Swanson, the rest of the sport soon got on board.

“Ultimately, catchers have just gotten too good at deceiving umpires, and the next step is potentially adjusting the rules to try to balance things out,” Swanson said. “That's how I see it.”

For catchers in the minors now, it’s difficult not to wonder what those adjustments will mean for how organizations evaluate — and compensate — them.

“That absolutely gets brought up,” Frawley said of a future in which pitch framing is replaced by robo-umps, “and we've quickly just told them, we will adjust to that if and when.”

Of course, that eventuality can seem rather immediate for guys catching in leagues already experimenting with ABS. The Twins at least are adamant, though, that they continue to train for human umpires, which means coaches at those levels have to regularly remind their catchers not to change how they receive pitches but to continue to present them as strikes — even where it no longer matters.

“We do constantly need to remind them to not fall into any traps relative to those systems,” Frawley said. “Because right now, if they end up in the big leagues, it's going to be your traditional umpiring crew. So that’s our tact right now. I don't know whether [other] orgs are sticking to that same messaging.”

“We've kind of started to shift away from not putting so much importance on it,” Veronica Alvarez said about pitch framing. She works in player development in Latin America for the Oakland A’s and spent the past few years as an independent contractor coaching catching at their affiliate levels, at spring training and in instructional leagues.

“So setting ourselves up for success as far as remaining adjustable to pitches and things like that, as far as when we receive the ball. But the framing part, there’s a little less focus on it. We still do it, just less than before.”

“We've talked about this a lot,” Swanson said. “I'm not certain that we would do anything different from a tactical standpoint.”

What he means is that the knee-down setup he evangelizes for its framing benefits is also effective for the blocking and throwing parts of catching that won’t be as impacted by ABS. Still, the role of the position and the skills teams prioritize stand to change drastically in coming seasons.

The embrace of a totally rigid strike zone and the loss of framing as an art form — or a valuable, teachable skill that catchers practice and take pride in — is enough for coaches and coordinators to lament the advent of ABS. Initially, though, ABS would seem to increase the value of other catching skills, especially those that go into controlling the running game. Frawley hopes it will highlight guys who excel at game-calling and what he termed “targeting” — setting up in a way that helps a pitcher hit his spot.

But beyond that, there’s concern about the broader consequences of de-emphasizing defense.

“Eventually, I think it'll go to the point where it's like, all right, just give me a body that can catch the ball but hits,” Alvarez said.

That could usher in an entirely new era of guys behind the plate.

“The defensive-centric catchers take a lot of pride in that part of their game, and they spend a lot of time and energy dissecting opposing lineups and game-planning and working with pitchers,” Swanson said. “I guess one of the potential fears is that you insert a player into that position that doesn't have a lot of vested interest in maximizing the performance of the pitcher or limiting base runner advancement or gaining strikes or preventing runs. They're back there with the sole purpose to drive in runs, really.

“And so, I'd be curious to know, what does the preparation look like? Or how does it change when you shift the general mindset of the player from one that's really defensive-oriented and cares deeply about getting hitters out and preventing runs versus somebody who is literally getting paid and the message is being sent from the league and the front office that we're putting you back there to be another offensive weapon to help us score runs. What's the ripple effect from that? How does that impact pitchers and the game-calling and so forth?”

All that, plus the loss of the dynamic tension between hitters, pitchers and umpires — and the fans who heckle them — leaves Swanson apprehensive about ABS.

“I'm not sure it would lead to a better brand of baseball,” he said.

What about challenges?

The challenge system is easier for catching gurus to embrace.

“It's an upgrade over the full-blown version [of ABS],” Swanson said. (Managers faced with navigating the tricky clubhouse dynamics of players empowered to demand the use of limited replay only on their own behalf don’t necessarily agree.)

In fact, Frawley sees a future in which a challenge system could actually enhance the importance of framing. Only the catcher, pitcher and batter are supposed to be able to challenge pitch calls, but he says it’s tough to imagine how the rule could prevent other players and coaches from emphatically weighing in based on what they see.

“The catcher is now tasked with not only tricking the umpire but also the hitter in the box and, honestly, the dugout as a whole because while you can’t challenge, sometimes there's going to be some guys in the dugout that give you the heads-up that it’s clearly down or clearly up,” Frawley said. “You're not just tricking the guy behind you but also the guy in front of you and the players to your right or left.”

And while some players certainly have better eyes than others, as evidenced by their ability to take close pitches for balls, the early results of the challenge system indicate that pro baseball players don’t know the rulebook strike zone as well as they might think. In the Arizona Fall League last year, only a third of challenges were successful. That’s a drop-off from what it was in the minor-league season, but even in the Single-A and Triple-A leagues that experimented, fewer than half of challenges were successful.

Those numbers would surely improve as players adjusted to a by-the-book zone and adopted a more targeted approach to challenges. But even so, going that route instead of ABS preserves what catching coordinators see as the primary goal of good framing: converting the borderline pitches, the kind that are unlikely to be challenged, into strikes more often than not.

Consider the larger ecosystem

Modern umpires are remarkably good. Under MLB’s evaluation system, which includes a buffer zone for “acceptable” calls, the league-wide average was 97.4% accuracy in 2021. Third-party and public grading accounts are a little tougher, but even by those metrics, big-league umpires call well over 90% of pitches correctly. Younger umpires are more accurate than the old guard, and a huge swath of old-school umpires with subjective strike zones are set to retire ahead of next season.

It doesn’t matter. The technology exists to turn a maddeningly imperfect system into something absolute and resolute. In an era of on-screen K-zones — which are an entertainment product, not an actual grading system — and missed calls gone viral, the ability to automate perfection makes implementation of ABS all but inevitable.

But a game called by a robo-ump will not simply be one officiated by a human with 100% accuracy on that particular day. The intent is to impact the purview of the umpire; the effect will change catching as we know it. Swanson went as far as to wonder whether there would be enough incentive to catch the ball at all.

“Which I think is problematic,” he said.

None of this means ABS is necessarily a bad idea. Baseball evolves, and in some ways, the current game is overdue for radical evolution, a shakeup that forces unforeseen adaptations. (Given contemporary concerns, trading defensive intricacy for additional offense could even be considered a desired outcome.) But the caveat from catching experts is to consider the ecosystem in which the strike zone exists, one in which umpires are not the only forces acting on it.

“They’re definitely not catchers,” Alvarez said of those pushing for ABS. “I can’t imagine that a catcher said, ‘Let’s do an automated strike zone.’”