J.T. Realmuto has escaped a few injuries already. What would the Phillies do without him?

J.T. Realmuto expected a down-and-away slider and set up accordingly on the outer part of the plate. Instead, Yunior Marte uncorked a sinker, 98 mph and tailing in to the right-handed batter.

And once again, the Phillies held their breath.

Realizing that he and Marte got their signals crossed, Realmuto moved his mitt at the last second. But the pitch clanked off the outside of his left wrist and skipped away, doubling him over in pain and enabling a run to score from third base.

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It sure looked like Realmuto broke his wrist. But even after an on-field examination by assistant athletic trainer Joe Rauch ruled out the worst-case scenario and Realmuto shrugged off the sting to stay in the game Friday night, the ironman catcher’s second injury scare in four games served to reconfirm what we have all known for a while.

Realmuto is the Phillies’ most irreplaceable player.

And it isn’t particularly close.

No offense to backup Garrett Stubbs, popular in the clubhouse for his taste in celebratory music, red-pinstriped victory overalls, and general good nature as a teammate. But there’s a reason why Realmuto plays more often than any catcher in baseball.

Since 2019, his first year with the Phillies after being acquired in a trade from the Marlins for pitching prospect Sixto Sánchez and catcher Jorge Alfaro (how’s that for a steal by erstwhile general manager Matt Klentak?), Realmuto has been behind the plate for 501 more innings — or the equivalent of 55 more games — than any catcher, not including the postseason. He has 21.3 wins above replacement, according to Fangraphs, 14th among all position players. Will Smith of the Dodgers is second among catchers with 16.5 WAR.

“He’s such an important part of the team,” Kyle Schwarber, a former catcher, said last week.

Indeed, for the Phillies, the drop-off to a replacement-level player is steeper at that position than at any other.

The Phillies withstood losing Bryce Harper with a broken thumb in 2022 and last year while he recovered from Tommy John elbow surgery. And although it would be difficult for them to stomach an absence for Zack Wheeler, they survived without him for a month down the stretch in 2022 when he dealt with a touch of right forearm tendinitis.

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How on earth would they replace Realmuto?

Surely, the thought flashed through the minds of team officials as Realmuto clutched his wrist Friday night at Citizens Bank Park. Or last Tuesday night in St. Louis, when the catcher staggered for a moment after a dirt-diving curveball clipped him in the throat under the mask, causing momentary dizziness and a longer-lasting headache behind his right eye but not a concussion.

The Phillies’ catching arrangement is different from almost every team, especially for the rival Atlanta Braves, who had a 60/40 split in playing time last season between veterans Sean Murphy and Travis d’Arnaud. When Murphy strained an oblique muscle in his side on opening day in Philadelphia, the Braves were set up to replace him with d’Arnaud, an All-Star in 2022.

But most free-agent catchers are seeking more playing time than the Phillies are able to offer. And the Phillies traded their best catching prospect, Logan O’Hoppe, at the deadline in 2022 for outfielder Brandon Marsh.

Stubbs made 32 starts — slightly more than one per week — in each of the last two seasons. He started back-to-back games four times and never three in a row.

Behind him, the Phillies were happy to re-sign 31-year-old Aramis Garcia to play at triple-A Lehigh Valley and picked up well-traveled 29-year-old José Godoy late in spring training. Garcia has made 75 major-league starts behind the plate; Godoy has made 18.

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So, the Phillies have insurance in case Realmuto were to miss two weeks with a minor injury. But a long-term absence would be an almost inconceivable blow.

The Phillies take Realmuto’s toughness as a given. Stubbs didn’t leap for his equipment in St. Louis because Realmuto rarely leaves a game. It wasn’t until he got to his feet and still appeared wobbly that Stubbs snapped into action.

“That guy’s a gamer, man,” pitcher Aaron Nola said. “I don’t think I’ve seen J.T. ever come out of a game. To get that guy out of the game, I guess you’ve got to hit him in the throat.”

The Phillies shudder to think about what more it would take.