As Jacob deGrom had hoped, the two-time reigning National League Cy Young Award winner will wind up missing only one start due to neck stiffness. deGrom threw a bullpen session Monday in Miami without issue, lining him up to pitch Wednesday against the Marlins.

“After seeing the side [session], he just needs to show up,” Mets manager Luis Rojas said, laughing. “He looked really good.”

That is welcome news for a Mets rotation dealing with multiple injuries and stretches of poor performance. No one is capable of stabilizing it in quite the same way as deGrom, who is 2-0 with a 2.45 ERA in four starts this season. deGrom had been scheduled to start last Friday against the Phillies, but the Mets scratched him that morning due to neck stiffness.

At the time, deGrom called the move precautionary, saying he could have pitched through the injury but did not want to make anything worse.

Also good to go is rookie left-hander David Peterson, who complained of mild shoulder soreness after his last outing. Peterson will start Tuesday in Miami, followed by deGrom on Wednesday.

But after that, things are still uncertain
One pitcher the Mets are not committing to is lefty Steven Matz, who owns a 14.66 ERA in three August starts. Matz has been working with pitching coach Jeremy Hefner to iron out issues regarding his release points and pitch sequencing, which the Mets believe have contributed to his propensity for “blow-up innings.”

“What we have ahead of us right now is to work on some things, fix some things to put him in the best situation that he can succeed,” Rojas said. “Matz is a hard worker by design. That’s one thing that helps us come in and coach him, work with him.”

Not until Matz throws his between-starts bullpen session will Rojas and Hefner determine if he will make his next start. Last year, amid similar struggles, Matz benefitted from a temporary move to the bullpen, posting a 4.95 ERA in 16 starts before that reassignment and a 3.52 ERA in 14 starts upon his return to the rotation.

But if the Mets want to make a similar move this year, they won’t have an easy way to replace Matz in the rotation Thursday against the Marlins. One candidate, Walker Lockett, allowed five runs in a spot start last week. Franklyn Kilome has never started a big league game. Corey Oswalt has an 11.81 ERA in the big leagues the past two seasons, and recent acquisition Ariel Jurado has a 5.85 mark. The Mets have also said repeatedly that they have no plans to move Seth Lugo from the bullpen.

Given all that, it’s possible the Mets could default back to Matz, whose mid-90s fastball and four-pitch mix offer more upside than their realistic alternatives. They will make a final decision in the coming days.

“Right now, we’re not committing either way to what’s going to happen,” Rojas said.

McNeil back, but not in the field
All told, Jeff McNeil missed two games after being carted off the field Thursday in New York. McNeil suffered only a bone bruise in his left knee from that incident, returning to game action as a pinch-hitter on Sunday.

On Monday, McNeil was back in the Mets’ starting lineup at designated hitter. He should be cleared to return to the field later this week.

Roster move
The Mets added yet another future star to their 60-man player pool, inviting their top overall prospect, shortstop Ronny Mauricio, to work at their alternate training site in Brooklyn. The move came days after the Mets added No. 2 prospect Francisco Alvarez and No. 5 prospect Matthew Allan to their player pool.

While the transactions technically make Mauricio, Alvarez and Allan eligible to make their big league debuts this season, team officials have described the moves more as a way to give them competitive practice time in the absence of a Minor League season.

The transactions also make them eligible to be traded before the Aug. 31 Deadline.

From the trainer’s room
Catcher René Rivera, who landed on the 10-day injured list last month due to a hyperextended left elbow, is actually suffering from a bone spur in that joint. He will undergo surgery on Wednesday to have it removed.

The procedure will likely end Rivera’s season. He had been the Mets’ third catcher behind Wilson Ramos and Tomás Nido.

In Rivera’s absence, prospect Ali Sánchez will assume that role if needed. The Mets transferred Rivera to the 45-day injured list to clear his spot from both their 40-man roster and 60-man player pool.