The Mets received some welcome good news on Wednesday, when an MRI on David Peterson’s left shoulder revealed no structural damage.

The left-hander, who was diagnosed with minor inflammation in the shoulder, was scratched from his start on Tuesday and placed on the 10-day injured list.

“I'm not worried about it,” said Peterson, who added that he’s dealt with a similar issue in the past. “I woke up yesterday [and] didn't feel right. I talked to the training staff and then we all made the decision to get it looked at.”

The Mets’ rotation has been in shambles throughout the season, dealing with the absence of Noah Syndergaard (Tommy John surgery), Marcus Stroman (calf injury, then elected not to play the season) and Michael Wacha (right shoulder inflammation), the last of whom has been on the IL since Aug. 8. The club has already used eight starters, who are a combined 7-10 with a National League-worst 5.49 ERA.

Manager Luis Rojas said that although Peterson isn’t ready to begin a throwing program, the expectation is that some rest will help the 24-year-old’s shoulder calm down so he can begin his road to a return.

“The rest is what's going to help right now,” Rojas said. “Then we'll see how he is and in a few days how he's responding to that rest and how the inflammation comes down for him.”

Peterson had been a bright spot for the Mets, going 3-1 with a 2.91 ERA in his first four career starts. There is no firm timetable for Peterson’s return, but he’s hopeful that his IL stint won’t be lengthy.

“I think the starts that I've had already have been good experience for me,” Peterson said. “There was things to learn and there was things to take away that were positives. I don't see this as a big block in the road; I'm going to take the experience that I've had and keep learning when I get back in the rotation.”

Sim success

Rojas said Wacha “felt good” after throwing 59 pitches over four innings of a simulated game on Tuesday at the Mets’ alternate training site in Brooklyn.

The manager said Wednesday was a “key day” to see what type of soreness or fatigue Wacha felt after his sim game. There is no set plan for what will come next for Wacha, Rojas said.