Carlos Carrasco may not reach the 170 innings pitched to...

Carlos Carrasco may not reach the 170 innings pitched to have his option kick in for next season. Credit: Jim McIsaac

ATLANTA — Carlos Carrasco’s new injury is going to cost him three to four weeks and potentially a whole lot of money.

An MRI revealed what the Mets called a low-grade strain of his left oblique, the team announced Tuesday afternoon. That means their pitching depth is a tad shallower now, with lefthander David Peterson likely slotting into the starting five in the interim, and brings to a halt what had been a strong season for Carrasco, who has a 3.92 ERA and was the only member of the regular rotation who had not been on the injured list.

Manager Buck Showalter wanted to take an optimistic view.

“Actually, pretty good news. Grade 1 — that’s good news. We thought it could be something a little deeper,” he said. “Let’s face it, Carlos I think has made more starts than anybody on our staff. I actually look at it as maybe it’s an opportunity to kind of freshen him up arm-wise a little bit. He was doing some things that nobody really expected. You hoped he would, but I think he’s exceeded the things that we thought he might do.”

With Carrasco out, Peterson and righthander Trevor Williams are lined up to start the doubleheader games Saturday against the Phillies.

The injury may well hurt Carrasco financially, too. His contract includes a team option for $14 million for 2023 that would become guaranteed if he meets two conditions: throws at least 170 innings this year and is expected to be healthy heading into next year.

All season, Carrasco had been on track to hit those benchmarks, including totaling 126 1/3 innings across a team-high 23 starts. But now, with him sidelined for at least the better part of a month, the magic number of 170 will be highly difficult for him to reach.

The Mets still would be allowed to pick up the team option (or pay a $3 million buyout). But with so many pending free agents, including starters Chris Bassitt and Taijuan Walker, they might choose to spend that $11 million difference in ways other than on a will-be 36-year-old with a lengthy injury history.

Personnel news

A bevy of roster moves Tuesday, after a bullpen-heavy game Monday, included righthanders Stephen Nogosek and R.J. Alvarez being called up from Triple-A Syracuse.

Alvarez gave up three runs and three hits in the third inning.

“A couple of fresher arms,” Showalter said. “Not fresh. Fresher. Nobody is fresh this time of year.”

The Mets also sent down righthander Adonis Medina (in addition to putting Carrsaco on the IL).

To clear a spot for Alvarez on the 40-man roster, the Mets designated outfielder Nick Plummer for assignment.

He is the answer to a trivia question: Who was the first player the Mets signed to a major-league contract under general manager Billy Eppler? They did so last November, when they took a chance on Plummer despite his having never reached the majors.

Plummer had a couple of nice moments with the Mets — including his first hit, a tying home run in the ninth inning against the Phillies on May 29 — but had struggled overall, including posting a .687 OPS with Syracuse.

Hunter watch

The Mets moved Tommy Hunter’s rehab assignment to High-A Brooklyn. He is eligible to return Sunday.