NEW YORK -- File this under “early Summer Camp surprises.” When the Mets set up their first simulated game Sunday at Citi Field, Yoenis Céspedes participated not just as a designated hitter, but also for an inning in left field.

The assignment was part of Céspedes’ defensive progression, though manager Luis Rojas stopped short of saying he expects the former All-Star to be ready to play a full nine innings by the end of camp. That will be a joint decision by the Mets’ coaching and training staffs, and will depend upon how Céspedes continues to progress on his road back from multiple heel surgeries and a fractured right ankle.

“We have to see. We have to keep going,” Rojas said. “That’s a progression. It was a good day today. I want us to keep building off of it. Our tight communication with the performance staff will dictate that. It was a positive day to get him out there with the rest of the guys, being in left field -- it’s been a while being here in Citi Field.”

It had been 26 months since Céspedes last manned the position even for practice reps at Citi, though he did so earlier this spring at the Mets’ Port St. Lucie, Fla., complex.

The Mets do not necessarily need Céspedes to contribute much of anything in the outfield, considering they can DH him whenever they see fit. Still, Céspedes’ ability to play left could result in additional plate appearances, given a crowded DH situation that may also include Dominic Smith, Pete Alonso, Robinson Canó, J.D. Davis and Jed Lowrie. It could also conceivably upgrade the Mets’ defense, if Cespedes even approaches the form that made him a Gold Glove Award winner as recently as 2015.

“That’s his first day out there in a sim game with us in left field,” Rojas said. “We’re going to keep monitoring him and see how he feels, and get the feedback on it. I talked to him a little bit in the gym, I saw him afterwards, and he feels pretty good getting out there and getting the at-bats and being with the rest of the guys.”

Summer Camp debuts
Shortstop Amed Rosario and pitcher Marcus Stroman both debuted at Summer Camp on Sunday after sitting out the first two days of team workouts. The Mets did not give a reason for either player’s absence.

Rosario did not participate in the early simulated game with the rest of the Mets’ starting position players. He instead took the field later in the day with a group of backup infielders.

“Not everyone is expected here on a daily basis,” Rojas said. “I’m not going to get into details of that, but there is a variety of reasons for that matter.”

Ninth-inning intrigue
Much like in February and March, Rojas committed to nothing when asked Sunday about his closer situation. The manager shied away from calling Edwin Díaz his primary option in the ninth, mentioning Dellin Betances, Seth Lugo and Jeurys Familia by name as alternatives. He also indicated that a closer-by-committee situation is possible.

“You know what, I don’t know yet,” Rojas said. “We have so many individuals that can do different things. … We have guys that have done it before. You can say you can go by committee. So there are a lot of things to see and we’re just going to enjoy it in camp. We’re just going to enjoy guys progressing with their matchups and their progressions, and we’ll get there at some point.”

Díaz struggled in his first year in New York last season, producing a career-high 5.59 ERA with seven losses and seven blown saves.

As for Betances, who faced seven batters in a simulated game Sunday, the right-hander called the three-month shutdown “a blessing in disguise” because it allowed him to rehab his partially torn left Achilles tendon more fully. Betances spent much of April through June working out at Impact Zone in New Jersey, where he recently threw live BP sessions to big leaguers Aaron Judge, Todd Frazier, Joe Panik, Aaron Hicks and Mike Ford.

“I know I feel better,” Betances said. “I know it’s coming out a little better. I feel like with the amount of games we have, I’ll be ready for the season.”