WASHINGTON -- Even as mild injury concerns dogged Jacob deGrom on his 33rd birthday, the pitcher’s ability to continue improving into his mid-30s stood above all else. Asked Saturday morning if he felt any older, deGrom grinned.

“No, I feel good,” he said. “I’m going the other way.”

It’s difficult to argue. deGrom holds the lowest ERA in Major League Baseball, by far, at 0.54. He has thrown multiple 102 mph pitches this season and remains the hardest-throwing starting pitcher in the game, also by far.

The only question is deGrom’s health. He continued answering that with a routine bullpen session on his birthday at Nationals Park, where deGrom said he “was letting them go, and everything felt good.” Although deGrom stopped short of committing to his next start on Monday, he admitted that the only way he wouldn’t start is “if I feel terrible [Sunday], and I don’t anticipate that.”

So consider deGrom’s latest injury scare put to rest. The two-time NL Cy Young Award winner left his last start after three perfect innings due to right shoulder soreness, which he believes he aggravated on a swing-and-miss at the plate. But an MRI came back normal, he played catch the following day, and he has since thrown both of his routine between-starts bullpen sessions without issue.

deGrom said he and the Mets briefly discussed shutting things down for a few days to be overly cautious, but after conversations with multiple doctors and members of the team’s training staff, no one believed that to be necessary.

“That was the discussion,” deGrom said. “But after going through, getting images on it, seeing the spot it was in and how it’s responded the past couple of days, I decided to try to proceed as normal. It felt like it’s nothing internal. It’s more muscular stuff. So we got it to calm down with the treatment we’ve been doing, and then throwing these past couple of days, it felt really good.”

Of greater concern is the fact that deGrom has now dealt with four separate issues since Spring Training -- back soreness, right lat and side soreness, right flexor tendinitis, and right shoulder soreness. But he does not believe any of the issues are related, which gives him peace of mind.

“I normally get sore back there when I pitch, but not during the game,” deGrom said of his right shoulder. “So I think I aggravated it, and then was feeling it when I was on the mound. So I felt like that was the right move to say something. Feeling it throwing is not ideal. I didn’t want to change anything with my mechanics and end up injuring something else.”

Simply put, the Mets trust deGrom to be truthful. Now 33, he understands his body as well as any pitcher in baseball. When deGrom tells the Mets he is good to go for Monday, they trust that he will be able to do so without issue.

Roster moves, present and future
The Mets activated reliever Yenssy Díaz to serve as their 27th man for Game 1 of Saturday’s doubleheader, with plans to make a series of additional roster moves in the coming days. Outfielder Albert Almora Jr. is set to come off the IL before Game 2 at Nationals Park.

Then there is Jeff McNeil, who is rehabbing from a strained left hamstring at Triple-A Syracuse. The Mets debated bringing McNeil to Washington to activate him on Sunday, but with lefty Patrick Corbin set to pitch for the Nationals, team officials decided to wait until Monday. McNeil will join the Mets in New York and be activated in time for their doubleheader against the Braves.

Pitcher swap
The Mets made a minor trade on Saturday afternoon, dealing right-hander Jacob Barnes to the Blue Jays for another pitcher, Troy Miller. The Mets had designated Barnes for assignment earlier this week and would have needed to place him on outright waivers had they been unable to complete a deal.

Miller, 24, had been pitching for the Blue Jays’ Double-A New Hampshire affiliate, where he posted a 7.20 ERA in three starts and a relief appearance. Prior to that, Miller had produced a 1.84 ERA over three starts for High-A Vancouver.

Mostly a reliever at the University of Michigan, Miller converted to starting pitching after the Blue Jays signed him as an undrafted free agent in 2018. He has since gone 9-10 with a 4.72 ERA over three Minor League seasons mostly spent as a starter.