WASHINGTON -- Almost every day this season, Gabe Kapler said, J.T. Realmuto would tell the Phillies manager that not only was he ready to play that night, but he was feeling healthy. They rode Realmuto all season, starting him more than any Phillies catcher in 20 years.

But the team’s durable catcher may not be able to finish the season after he felt knee soreness Sunday night and missed the series opener Monday against the Nationals to undergo an MRI exam. The Phillies entered Monday trailing the Nationals and Brewers by six games with eight to play. They have been all but eliminated from the wild-card race and it may not be worth it to risk Realmuto’s health.

“I want to make sure that there’s nothing I can damage further. If there is, then we’re going to be smart about it,” Realmuto said.

“Because we all know where we stand right now in the standings. I don’t want to push it and risk hurting myself for next year or anything like that. But if there’s nothing structural-wise that I can make worse, then I want to be back there with my teammates and I want to play the last few games of the year. I love to play this game, so I want to be out there if I can, but we’re going to be smart about it.”

Realmuto said he felt discomfort Sunday night in Cleveland after returning from hitting a double-play grounder in the fifth inning. His knee, the catcher said, “kept popping every time I moved it.”

Realmuto felt a little more pain Monday morning and told Kapler. The manager wanted to be cautious with the player who always told him he was ready.

“To be honest with you, I’ve had a little issue in the back of my knee for the last two or three years,” Realmuto said. “I don’t know if this is just an instance where it finally flared up enough to feel it a little bit more, but I felt fresher this September than I’ve ever felt in any years in the past. I don’t think it has anything to do with the workload. I just think it was just a bad luck kind of thing.”

Realmuto caught 133 games, more than any catcher in baseball and the most by a Phillies catcher since Mike Lieberthal caught 143 in 1999. He leads all major-league catchers in games played, has accumulated the most WAR, and has thrown out the most attempted base stealers.

Realmuto’s 36 doubles are the most ever by a Phillies catcher and he has set career highs in home runs and RBIs.

General manager Matt Klentak said last week that Realmuto has “been everything we could have asked for” after the team parted with pitching prospect Sixto Sanchez to land him from Miami. The Phillies will try to sign Realmuto this winter to a long-term contract, since he can become a free agent after 2020. Realmuto said earlier this season that he would be open to it.

“Let’s look at this objectively: What we’ve gotten out of J.T. has been damn near perfect,” Kapler said. “What’s happened year-to-date with J.T. couldn’t have gone any better for the Phillies and couldn’t have gone any better for J.T. Realmuto. I’m not sure the model of anything else is better.

"Granted, would we like him to be healthy for today’s game? Absolutely. But for the most part, this has been a very healthy, very durable, very productive, excellent player for us all the way through the season. And in a lot of ways stronger in the second half than he was in the first.”

Extra bases

The Phillies will start righthanded reliever Blake Parker for the first game of the doubleheader Tuesday against Nationals righthander Joe Ross. ... Aaron Nola will start Tuesday night in the nightcap against righthander Max Scherzer. ... Roman Quinn ran sprints Monday afternoon and remains a candidate to return this season, Kapler said.