Martinez thrilled to jump on board at last

Afew hours before his long-awaited Mets debut, J.D. Martinez said he just wants to fit into the lineup and contribute. It’s unfair, manager Carlos Mendoza added, to put too much pressure on the veteran designated hitter.

Still, an air of excitement hung over Citi Field on Friday with the six-time All-Star finally in the Mets’ lineup — hitting fifth, behind Pete Alonso — for the first time.

“I made it,” Martinez, standing in front of his new locker, said with a laugh before the Mets’ series opener against the Cardinals.

The Mets called up Martinez, 36, on Friday after signing him to a one-year, $12 million contract in late March. Martinez, one of numerous big-name Scott Boras clients to endure a prolonged free agency in the offseason, had hoped to debut sooner, but lower back tightness set him back during his extended spring training in Port St. Lucie.

He watched from afar as the Mets slumped to an 0-5 start, rebounded with five consecutive series victories and finished off a 3-3 road trip this week against two of the West Coast’s toughest teams in the Dodgers and Giants.

“I want to, obviously, be a part of it,” Martinez said Friday. “If they’re struggling, I want to struggle with them. If they’re doing good, I want to do good with them. That’s part of being a team. Unfortunately, signing so late, I didn’t really get to know the guys and hang out with them, but I’m here now and I’m hoping to make an impact.”

The Mets hope Martinez — a .287 career hitter who recorded 33 home runs and 103 RBI last year with the Dodgers — can add protection behind No. 3 hitter Francisco Lindor and No. 4 hitter Pete Alonso.

The Mets tried out different batters behind Alonso, who entered Friday with 12 RBI, throughout the season’s first month. Among them was catcher Francisco Alvarez, who is set to miss eight weeks after undergoing thumb surgery.

“You look at every great team out there, and every elite lineup, and they have threats in the middle of the lineup that can hold it down,” Martinez said, describing the importance of lineup protection. “It puts [a] thought into the pitcher’s mind, into the opponents, of attacking guys early and trying to keep guys off base for the heart of the order.”

To make room for Martinez on the MLB roster, the Mets designated backup infielder Zack Short for assignment. Short appeared in 10 games but managed only one hit in nine at-bats.

Martinez’s call-up came after he played in three minor-league games this week with Single-A St. Lucie and Triple-A Syracuse, going 5-for-11 with four RBI.

The slugger, who has dealt with back issues since 2019, received a cortisone shot after experiencing the tightness during an initial minor-league stint in early April.

“I think I put too much emphasis on coming back,” Martinez said. “I tried to hurry back too quick, and my body just wasn’t ready.”

Mendoza said he’ll make sure to give Martinez regular rest, especially early on, in what he describes as a “fluid” situation.

He acknowledged, though, that he enjoyed putting Martinez’s name into Friday’s lineup.

“He’s just gonna make our lineup a lot deeper,” Mendoza said. “We’ve got really good hitters here, but having J.D. finally in our lineup, obviously, is a good feeling.”

SENGA SET FOR NEXT STEP

Mets ace Kodai Senga is set to throw a live bullpen session Monday, which would mark the pitcher’s first time facing hitters since suffering a right shoulder strain during spring training.

Senga, who is on the 60-day injured list, threw a bullpen session on Thursday. “(He is) feeling good today,” Mendoza said. Senga, who was diagnosed in February with a moderate strain of the posterior capsule in his shoulder, pitched to a 12-7 record, a 2.98 ERA and 202 strikeouts in 166.1 innings last season, his first since signing with the Mets from Japan.

MEGILL PROGRESSING, TOO

Tylor Megill, also recovering from a shoulder strain, is set to pitch two innings for High-A Brooklyn on Saturday, according to Mendoza.

Megill won Senga’s vacated spot in the rotation out of spring training but suffered his injury during his season debut on March 31.