NEW YORK -- A long-lost member of the Mets’ Opening Day bullpen could be nearing a return.

Dellin Betances began a Minor League rehab assignment with the Low-A St. Lucie Mets on Sunday, marking his first game action since his lone regular-season outing on April 7. Following that appearance, the Mets diagnosed Betances with a right shoulder impingement; he’s been working on strengthening the joint ever since.

In his debut at St. Lucie, Betances pitched a scoreless inning with two strikeouts.

“It’s a big day,” manager Luis Rojas said. “A big day for him. We expect him to be right.”

Mets officials will be watching closely to see if Betances’ fastball velocity, which hovered in the low 90s during Spring Training and in early April, can boost back into the mid 90s. Rojas said Betances was throwing 93-94 mph during his recent live batting practice sessions, without the adrenaline boost -- and corresponding velocity increase -- that game action tends to provide.

To be clear, the team is under no delusions that Betances, who spent years as one of the hardest-throwing pitchers in baseball, will ever approach triple digits with his fastball again. But the Mets believe he can be an effective pitcher with even modest gains on the radar gun.

“He’s had some really good reads with his fastball,” Rojas said. “We’re pretty optimistic about him going into this assignment and keeping ramping things up. … He’s been throwing really good. He did a good job in the progression, in strengthening the shoulder. He worked hard.”

Betances, one of former general manager Brodie Van Wagenen’s highest-profile free-agent signings before the 2020 season, has appeared in only 16 games as a Met with a 7.82 ERA. He is making $6 million this season with a $1 million player option on his contract for 2022.

No news is good news
Jacob deGrom played catch without issue for a second straight day on Sunday, keeping him on track to start Wednesday against the Cubs, despite his recent bout of right flexor tendinitis. deGrom is scheduled to throw a routine bullpen session on Monday. The Mets won’t commit fully to deGrom until he does so, but all parties involved expect no issues.

Lineup absences
Infielder Jonathan Villar and outfielder Billy McKinney were both out of the lineup on Sunday. Villar’s absence was due to a family issue; the Mets did not provide further details.

McKinney was sidelined a second straight day due to a sore right knee, but Rojas was optimistic his starting right fielder would be available off the bench. At the least, Rojas expects McKinney to be back in the lineup for Monday’s series opener against the Cubs.

“It sounds like something that built up playing the amount of days that he played in a row,” Rojas said.

Rehabbing Squirrel
As expected, second baseman Jeff McNeil began a rehab assignment on Sunday for High-A Brooklyn. The Mets expect McNeil, who has not played since straining his left hamstring on May 16, to spend approximately one week on assignment and return to the big club next weekend.

Outfielder Michael Conforto remains about a week behind McNeil in his own progression from a strained right hamstring. He is due back the final weekend of June, if not before.

Jeers to cheers
Before the end of the Mets’ most recent road trip, shortstop Francisco Lindor quipped that he hoped “when I get home, maybe I don’t get booed.” He was referring to Citi Field fans who had voiced their displeasure with his slow start throughout April and May, with increasing volume as the season had progressed.

But Lindor appears to have left his early-season slump behind, and the boos along with it. Upon homering in the first inning of Saturday’s win over the Padres, Lindor received perhaps his loudest ovation of the season. (Due to a significant capacity increase at Citi Field this homestand, the Mets played in front of their two biggest crowds of the season on Friday and Saturday.)

Entering Sunday’s play, Lindor had increased his OPS 178 points in five weeks.

“It’s a little bit of a relief,” Lindor said. “The first couple of games when I got booed felt like I was playing on the road. Now, it feels like I’m at home. And I want to thank the crowd for showing up and supporting the whole team. We win with them. We don’t win without them. They’re a big part of our success every single time, because they definitely put a lot of pressure on other teams.”