When Luis Rojas learned that David Peterson would not be able to make his start Tuesday night at Marlins Park, the manager didn’t panic. After all, he’s been through this before.

The Mets turned to Corey Oswalt, who answered the call with 4 1/3 innings of two-run ball in an 8-3 win over the Marlins, New York’s second straight win in Miami.

“We’ve been surprised a few times, but the preparation that we have, the depth that we have, it just helps to have a guy just jump in and respond right away,” Rojas said. “That was the case with Oswalt today, and that’s been showing since the first week of the season with Peterson.”

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The irony wasn’t lost on Rojas. Peterson got his first call to start in similar fashion, moved from the taxi squad after Marcus Stroman suffered a calf injury. Now it’s a Peterson injury that had the Mets scrambling again Tuesday, just four days after Walker Lockett was forced to make a spot start for an injured Jacob deGrom.

“It happened with Lockett last Friday and it happened today with Oswalt,” Rojas said. “They were the guys that stepped up. It happens and it surprises you, but at the same time, you're prepared enough with the depth that you have that there’s a guy who can come in and do what Oswalt did for us.”

Jonathan Villar opened the home half of the first with a single, but Oswalt kept his cool and picked him off for the game’s first out. The right-hander retired the next nine Marlins, breezing into the fourth.

“I found out I was starting when I got to the ballpark today,” Oswalt said. “I was excited getting out there, especially a start. I've been in roles like this before, so that helped me.”

Handed a three-run lead in the fourth, Oswalt gave back two runs in the bottom of the inning, but he stranded a pair of runners on base, preserving the lead.

“He picked off Villar, and after that, he was pretty much under control,” Rojas said. “Mixing his pitches, keeping the ball effectively down; he gave us a lot. For him to find out late that he was going to get the start tonight and to go out there and do that, it just shows that he was prepared.”

With Peterson (shoulder fatigue) on the injured list and Steven Matz still uncertain whether he’ll start Thursday, the rotation remains in a bit of disarray. Yet even after his solid spot start, Oswalt has no guarantees that he’ll get the ball again when the spot comes around in five days.

“Right now our focus is tomorrow's game,” Rojas said. “We’re going game by game.”

Swing king
Brandon Nimmo reaching base three times in a game is hardly news. The center fielder entered Tuesday’s game with a National League-high 22 walks and a stellar .423 on-base percentage.

Tuesday wasn’t a typical game for Nimmo, however.

“He didn’t walk and he got on base three times,” Rojas said. “That shows how aggressive he can be as well when he gets his pitches.”

Nimmo took Marlins righty Humberto Mejía deep on a 1-0 pitch in the third inning for the game’s first run, then tripled on a 2-1 pitch against switch-pitcher Pat Venditte in the fifth. An RBI single in the eighth in a typically lengthy at-bat (seven pitches) capped Nimmo’s 3-for-5 night, as he fell just a double shy of the cycle and increased his OBP to .431.

Even though he’s getting on base more than most players in the game, Nimmo has been trying to get more comfortable at the plate. Tuesday night was definite progress as Nimmo picked up only his second multihit effort in 17 games this month.

“It's still a work in progress, but we're definitely making a few positive strides,” Nimmo said. “I'm trying to put the ball in play a little bit better in early counts when I get the pitch; I was able to do that tonight, so that's a positive move. … Because I'm feeling a little bit better at the plate, I'm able to attack a little bit better earlier in the count.”

Rosario breaks out
Nimmo wasn’t the only Mets hitter to feel good about his night. Amed Rosario joined Nimmo (and J.D. Davis) by homering in the win over the Marlins, collecting his second straight multihit game thanks to a big two-run single in the eighth that helped turn a close game into a blowout.

Rosario’s lack of plate discipline is well known -- he hasn’t drawn a walk in 76 plate appearances this season, extending his streak to 129 plate appearances dating back to 2019 -- but the shortstop has been working to cut down on the pitches he’s chasing out of the zone.

Rojas was pleased with the progress he saw Tuesday.

“His approach has gotten better; he still chased a few pitches tonight, but better,” Rojas said. “Those are really good signs that he's seeing the ball better and he's trusting more on what he's committing to.”

Rosario had been 8-for-49 (.163) with one double, one home run and three RBIs over 13 games heading into the Marlins series. He’s gone 2-for-5 in each of the past two games, matching the production from those 13 games with one double, one homer and four RBIs.

“I feel like this season's been tough, but I've continued to work and have been keeping a positive attitude,” Rosario said through a translator. “I know that eventually with the work that I've been putting in that the results would eventually show.”