PORT ST. LUCIE, Fla. -- The Mets’ march toward pitching depth continues. After acquiring starter Chris Bassitt in a deal with the A’s, they agreed to terms on a one-year deal with reliever Adam Ottavino, the club announced Monday. The deal, per sources, is a $4 million contract.

Ottavino will join Edwin Díaz, Seth Lugo and Trevor May at the back of New York’s bullpen. He posted a 4.21 ERA in 69 appearances last year for the Red Sox, striking out 71 batters in 62 innings. Since 2018, Ottavino has averaged 11.9 strikeouts per nine innings while producing a 3.05 ERA for the Rockies, Yankees and Red Sox.

Swing-and-miss stuff has long been Ottavino’s forte; since 2018, he ranks sixth in the Majors in strikeouts by a reliever, trailing (among others) Josh Hader and Díaz. A technologically savvy pitcher who reinvented himself in the last decade in large part through the use of data, Ottavino is joining a team full of likeminded individuals, including pitching coach Jeremy Hefner and a rapidly expanding analytics team.

With Díaz in-house, the Mets don’t need Ottavino to close games as he’s done on occasion earlier in his career. They simply need him to slot into a middle- to late-innings role, sharing those responsibilities with Lugo, May, and perhaps another pending addition. The Mets’ top remaining roster need is lefty relief help, with Andrew Chafin a prominent free agent still available. Hader is also a long-shot trade option, while in-house possibilities include David Peterson and Thomas Szapucki, as well as non-roster invitee Alex Claudio.

“We have some lefties that are going to be in camp here,” general manager Billy Eppler said. “We remain open-minded to look at that group, too. We signed Alex Claudio, who has been extremely tough on left-handed hitters, so he’ll get a long look in camp. I’ll just always remain open-minded to adding where we can, but I don’t want to force the shot, either.”

No matter which direction the Mets go, it’s clear that they are not yet done shopping. Earlier Sunday, owner Steve Cohen said that he expected the Mets to exceed Major League Baseball’s new fourth Competitive Balance Tax threshold. That would require a payroll of more than $290 million, or roughly $10 million more than where they currently sit.

Any remaining expenditures are likely to come on the pitching side, as Eppler said he feels “fairly good about our position player group right now.”

“I’ll never rule anything out, but I’d be fairly surprised if we went after another bat or anything like that at this juncture,” the GM said. “I feel pretty good about where that sits right now, but I can’t say no to opportunity, I guess.”