After another subpar outing from David Peterson, the lefty was optioned to Triple-A Syracuse — again.

Peterson showed promise a year ago, but has not found any success this season — including in Monday’s outing against the Nationals that brought his ERA up to 8.08.

“Some things were better [Monday], believe it or not,’’ manager Buck Showalter said of Peterson’s latest dud. “But every time he made a mistake, it got whacked.”

This is the second time he’s been sent to the minors due to ineffectiveness.

With Carlos Carrasco set to return from elbow inflammation on Friday, it’s unclear when Peterson will get another chance in the majors.

“I told him [Tuesday] it’s good that I’ve seen him really good, because if it was just this year …’’ Showalter said of Peterson, without finishing the sentence.

He didn’t need to.

“Hopefully, Sunday is the start of him being a better option because we need him,’’ Showalter said before the Mets’ 8-5 loss to the Rays. “And if he doesn’t get it going down there, we’ll have to go in another direction. He knows. It’s not good enough, especially with what he’s capable of.”

Left-hander Josh Walker was recalled from Triple-A to replace Peterson on the roster. The 28-year-old Walker was drafted in the 37th round by the Mets in 2017 and made his MLB debut with a scoreless seventh inning in Tuesday’s 8-5 loss to Tampa Bay.

In nine games with Syracuse this season, Walker allowed just one earned run and had a WHIP of 0.900 in 13 ¹/₃ innings.

Jose Quintana could take an important step in his comeback from a fractured rib when he gets a CT scan on the area Friday.

Showalter called the upcoming scan “huge” for Quintana, who has been out since the spring, when he underwent bone grafting surgery.

“If it shows what we’re hoping, he’s off and running,’’ Showalter said of the left-hander.

Since Quintana has been able to throw during part of the recovery process, he’s ahead of where he’d be at the start of spring training.

He was expected to be out until July and Showalter made it sound like that remained a realistic time frame.

“Once we get clearance, he’ll start [rehabilitation] pretty quickly,” the manager said. “I don’t forget what he’s capable of.”

Showalter sounded encouraged about Omar Narvaez’s progress from a strained left calf that’s kept him out since the first week of the regular season.

Showalter said Narvaez is “doing well” and could start playing rehab games as soon as next week.

“It will be good to get him back,’’ Showalter said.

It’s unclear when catcher Tomas Nido might be back from symptoms from dry eye syndrome. Michael Perez is the backup catcher for now.

The Mets have gotten an OPS of just .582 from their catchers. Only four teams have received less production from that position.

Drew Smith was upset with home plate umpire Ben May because Smith said Jose Siri was late getting into the batter’s box in the eighth inning on a three-ball count. Smith said Siri didn’t get set until there were five seconds left on the pitch clock, which left Smith with little time to change his pitch selection.

“I wound up yanking the pitch and walking him,’’ Smith said. “[Siri] should have had a strike called there.”

Siri scored later in the inning.

— Additional reporting by Andrew Crane