The Mets’ rotation took another hit Tuesday as David Peterson was scratched from his start and placed on the injured list with left shoulder fatigue.

Peterson left last Thursday’s start after five strong innings against the Nationals, complaining of fatigue. He was expected to make his start Tuesday against the Marlins, but manager Luis Rojas said the left-hander “felt a little weird with his shoulder” when he woke up, informing the team of the issue.

“I went to bed last night thinking that David Peterson was going to be our starter,” Rojas said. “I woke up this morning thinking David Peterson will be our starter.”

Rojas said the Mets were evaluating Peterson -- who is 3-1 with a 2.91 ERA in his first four big league starts -- to determine whether he’ll be sent for any tests, but the IL move made sense.

“The decision [was] just to be more careful,” Rojas said. “It’s shoulder soreness, and we didn't even want to push it.”

Right-hander Corey Oswalt was recalled from the alternate training site in Brooklyn to make the start in Peterson’s place. The Mets also recalled righty Drew Smith, optioning right-hander Franklyn Kilome.

“It's another challenging thing for us in the season with the starting pitching, but the depth has helped us bounce right back and just keep going with our plan,” Rojas said of Peterson’s injury. “There’s a lot of things happening with the ramp-up with the season, guys just getting the soreness, getting injured; there are a lot of surprises.”

The Mets are already without Noah Syndergaard (Tommy John surgery) and Marcus Stroman (elected not to play) this season, while Michael Wacha is on the IL with right shoulder inflammation. Even Jacob deGrom missed his last start with a stiff neck, though he’s expected to pitch Wednesday against the Marlins.

“As of now, that's still the plan,” Rojas said of deGrom.

Wacha, who was eligible to return from the IL on Tuesday, threw a simulated game at the team’s alternate training site.

Waiting game for Matz
The Mets still haven’t decided whether Steven Matz will make his next start, as Rojas said the left-hander is trying to work on some of the issues that have haunted him during his rough start this season.

Matz is 0-4 with a 9.00 ERA in five starts this season, posting a 14.66 ERA in three August outings.

“We're still discussing with him things that we want to fix, things we want to work with him [on] … things that we’re working for him to translate into the game,” Rojas said. “We’re not committed either way yet.”

One big hurdle the Mets face is who would take Matz’s spot if he was skipped. Given the aforementioned pitching injuries, Rojas said the Mets are “not committed to anything” when asked about possible options.

Could Seth Lugo be a possibility? The right-hander has been used as a late-inning reliever, but Rojas cited Lugo’s versatility and ability to throw multiple innings while admitting, “It’s something to think about.”

“Seth can do different things,” Rojas said. “We're not committed with him yet to do something as an opener or something as a starter yet, but that's something that, you never know. His versatility can definitely help us to do some things different from the bullpen in the future. We’ll see.”

Reading the unwritten rulebook
Fernando Tatis Jr.’s eighth-inning grand slam on a 3-0 pitch with a seven-run lead Monday night caused quite an uproar around the game. Some criticized the young Padres star for breaking an unwritten rule, while others were dismayed with the old-school condemnation.

Rojas, the son of former longtime manager Felipe Alou, said he understood both sides of the argument.

“I was raised in the game in the traditional way where the unwritten rules were always respected,” Rojas said. “At the same time, I understand both opinions; the number of runs, the counts, I respect all that. I was raised in that unwritten-rule type of atmosphere. Right now, I see a lot of big innings build up easy and quick, so it's almost like there's no comfortable lead.”

Rojas added that when this type of incident occurs, managers have trouble trying to quell some players’ emotions. Rangers pitcher Ian Gibaut was suspended Tuesday for throwing at Manny Machado after the home run.

“That's where it can become delicate,” Rojas said. “Somebody can get hurt, people throwing at each other, and then it can really develop into something else.”

Dominic Smith had a different view of the incident, saying he was fine with Tatis’ decision to swing 3-0.

“I don't mind it, personally,” Smith said. “It's hard to hit, period. I've been in situations where I've gotten 3-0 cookies and I've taken them, the next pitch has been painted and then I’m striking out. Then I walk back to the dugout kicking myself in the butt because I didn't swing at that 3-0 pitch.”