For months, most Phillies fans rejected the idea of anyone other than J.T. Realmuto behind the plate. But the star catcher broke his thumb at the outset of spring training, a few weeks after #SignJT turned from a rallying cry into reality, and he has yet to play in an exhibition game.

How’s that for a heaping plate of irony?

In fairness, Realmuto’s injury resulted from a freak accident. He moved to block José Alvarado’s dirt-diving curveball, and the pitch glanced off his unprotected right hand before reaching his mitt. It happens — and to catchers of all ages, from 15 to 25 to 35 — and the Phillies remain hopeful that he will start the season on time.

But it’s also a fact that catchers don’t typically age well. Chalk it up to squatting 150 times per game for six months. And the toll of playing the sport’s most physically demanding position only builds over time. There’s a reason why many former All-Star catchers, from Joe Torre to Joe Mauer, changed positions in their 30s.

Realmuto turned 30 on Thursday. He isn’t about to give up his chest protector and shin guards after starting at catcher in 73.8% of his teams’ games over the last six years. But maintaining that pace — roughly 120 starts per season — for the duration of his five-year, $115.5 million contract will be enormously challenging.

“I’ve worked with certain doctors and certain trainers to try to keep my body in the best shape that I can to perform as long as I can,” Realmuto said recently. “Athletically I think I’m a little more advanced than most catchers are. As long as I continue to keep my body in shape I don’t see why I wouldn’t be able to last a little longer than other catchers.”

In the expansion era (since 1961), 49 catchers have played at least 120 games behind the plate in their age-30 season. The total drops to 36 catchers at age 31, 33 at 32, 24 at 33, and 18 at 34. Only four — Brad Ausmus, Jorge Posada, Jason Kendall, and A.J. Pierzynski — reached the 120-game mark in all five seasons from 30 to 34.

If there’s reason to bet on Realmuto to join the club, it’s his pedigree. He played mostly shortstop at Carl Albert High School in Midwest City, Okla., and likely would have stayed in the infield if he kept his commitment to Oklahoma State. He happened to be filling in at catcher one day in the spring of 2010 when two Marlins scouts showed up to watch him. Miami drafted him that June as a catcher.

“I basically started from scratch when I was 20 years old as opposed to most catchers that get to pro ball and have been catching since they were 8 or 9,” Realmuto said. “Who knows how much that puts on your body from such a young age?”

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But Realmuto is also taking steps now to help achieve catching longevity.

After ending the last two seasons with injuries — a meniscus tear in his right knee in 2019, a strained hip flexor last year — he asked the Phillies’ training staff to design a program to enhance his strength and flexibility. He also works with team dietitian Alexa Scully to monitor his eating habits.

Realmuto made another change within the last two years. He scrapped the traditional crouch and began catching with one knee down in order to improve his pitch-framing skills. But it served another, less intended purpose.

“My weight isn’t on my joints all the time as far as my ankles and my hips go. My weight is on my shin guards and my knees,” he said. “I’m not putting as much weight on my body, maybe as much as a traditional catcher. That could help me.”

Secrets to catching past age 30

It all adds up, according to veteran backup catcher Jeff Mathis. Two weeks shy of his 38th birthday, Mathis is in Phillies camp as a nonroster invitee and hoping to wind up in the majors for a 17th season. Last year, he was the third-oldest catcher in baseball after Erik Kratz and Yadier Molina.

What’s Mathis’ secret?

“The biggest thing for me is being able to keep my body limber,” he said by phone last week. “I’ve gone down several avenues with it, whether it’s working out, whether it’s stretching, whether it’s diet, really just trying to maintain that flexibility. Because the hips and the knees, low back, they can definitely get a little stove-up.”

Mathis doesn’t do yoga, though he said he often wishes he did. He sticks to a program given to him in 2017 by Arizona Diamondbacks head athletic trainer Ken Crenshaw that focuses on strengthening core muscles around the hips, glutes, and lower abs.

Over the years, Mathis has adjusted his training routine. He takes at least a month off now after a season “to let everything heal up,” and when he does get back in action, he works on flexibility before lifting a single weight.

“I pick his brain as much as I can to see what he has done to keep being able to catch this late in his life,” Realmuto said. “He looks just as good as he did when he was 30, and that’s something I want to be able to replicate.”

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Mathis figures Realmuto will need to adapt as time goes on. But as teammates with the Marlins from 2014 to 2016, Mathis was struck by Realmuto’s speed and pliability. Phillies manager Joe Girardi, a catcher for 15 years in the majors who retired at age 38, said Realmuto’s athleticism makes him a “freak of nature” among catchers.

“One thing about being athletic, there’s not a direct correlation to being flexible and elastic but it means you make movements that others aren’t capable of doing,” Mathis said. “That’s definitely something that will help him out in the future.”

Money records

Eleven years ago, Mauer signed a contract extension that paid him $23 million per year, a record for catchers. Realmuto beat that mark with the Phillies, but only by $100,000. He may never know if a pandemic-altered free-agent market kept him from raising the bar higher, or if most teams are just skittish about giving long-term contracts to catchers.

If it’s the latter, Mathis understands.

“It comes with the territory,” he said. “We always joke about this being something we signed up for a long time ago, the blocking drills at 8 o’clock in the morning [at spring training] or squatting down for a long inning, the foul tips. We picked this position.”

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And the Phillies gambled that Realmuto will stay there for the next five years. He has the athletic ability to play first base or even third, and the designated hitter likely will return to the National League after this season. But Realmuto’s value is highest as a catcher.

“Usually if you have quality performers, their aging process is a little bit different than others,” Phillies president of baseball operations Dave Dombrowski said. “He’s a quality performer. He’s athletic. He’s hardworking. Sure, maybe at 35 you’re not the same at 34 or the same at 30. But when you start from where he is to where it would be, we look at that as being a quality big-league performer at that time.”

Even if it goes against the aging pattern of most catchers who came before him.