J.D. Martinez locked and loaded as Red Sox DH

J.D. Martinez has been one of the best hitters in the majors for the past six seasons.

In his two years with the Red Sox, Martinez has performed above his pay grade. The veteran designated hitter signed a five-year, $110 million deal prior to the 2018 season under former Red Sox president of baseball operations Dave Dombrowski. Martinez and Dombrowski had a history dating back to their days with the Detroit Tigers.

The Sox and Dombrowski brought Martinez on board to be a fixture in the middle part of the order, allowing Rafael Devers and other younger players to develop around him.

It worked, and then some.

The Red Sox’ World Series championship in 2018 had Martinez’s imprint all over it. He hit .330 with 43 homers while driving in a league-leading 130 RBIs. Despite being a DH, Martinez finished fourth in MVP voting and took home two Silver Slugger awards, including his first as a DH. That was just his production on the field.

J.D. Martinez has 235 RBI in his two seasons with the Red Sox.John Tlumacki/Globe Staff

Outside the lines, Martinez is as routine-oriented as they come. He scours through video on the mechanics of his swing. After being released by the Astros earlier in his career, Martinez had to revamp his entire swing and approach. He felt he had too steep of a swing and instead went for more of a launch approach.

He brought some of his Red Sox teammates along for the ride with his approach — particularly Mookie Betts, who purposely hits in the same batting practice group as Martinez.

“I remember last year, it was his first year and everyone wanted to go to J.D. for advice. Even me a couple times,” Xander Bogaerts said during All-Star week in Cleveland last season. “Whenever stuff isn’t going right, you either go to the hitting coach or you go to J.D. He’s definitely changed a lot of us on this team with the mind-set and the advice. He’s definitely huge.”

Martinez got off to an uncharacteristic start at the beginning of 2019, but in the end his numbers were there. He still managed to hit .304 with 36 homers to go along with a .939 OPS, the latter of which tying him with Bogaerts for first on the team. Additionally, he was second in the league in homers and OPS for players at his position, just behind Nelson Cruz.

One of the bigger questions heading into the offseason was if Martinez would opt in on his $23.75 million deal for 2020. At All-Star week, Martinez expressed that he would like to stay in Boston, noting that it was his favorite team. However, he also redirected any type of contractual questions to his agent, Scott Boras. Had Martinez opted out he would have been a 32-year-old free agent, but Boras didn’t see that as an issue.

“The age component is no different than David Ortiz,” Boras said last July. “David Ortiz’s age did not affect his performance because he was David Ortiz. So, when you go through all of this and look at it, maybe you can say that the 31-, 32-year-old player doesn’t get the 10-year contract, but on the other hand it has nothing to do with what his average annual value will be because that production is so rare.”

J.D. Martinez crosses home plate in front of Orioles catcher Austin Wynns after a September homer.John Tlumacki/Globe Staff

Martinez certainly produced but he prudently opted in, too.

As a result, the Sox have Martinez for at least this season.

“J.D. wanted assurance of competition at a high level and the fact that he played so well in Boston, we looked at it and with those two things in mind, we wanted to make sure that was the focus and for that reason he decided to opt in,” said Boras.

Martinez has two more opt-outs at the end of the 2020 and ’21 seasons. He could earn $19.35 million in each of those years. Considering his age and his market as a DH, it’s hard to imagine Martinez taking a risk by opting out. While he was capable of playing the field in the past, Martinez mainly profiles as a DH now. He posted a -4.8 Ultimate Zone Rating despite playing just 330⅔ innings in the outfield last season. The last time he registered a positive UZR came in 2015 with the Tigers.

His bat, though, hasn’t shown any signs of slowing up, and despite dealing with a bad back at certain points of 2019.

Martinez’s name is cemented into the DH spot, but on his days off Bobby Dalbec, Devers or Michael Chavis could slide into the role. The Sox could also do what they did on occasions last season: put Martinez’s in the outfield, substituting offense for defense.

Regardless, the Sox have their DH and he has produced at a high clip. More importantly, Martinez will do everything in his power to stay at that level.

“We play 162 games and you might feel like your swing feels really, really good, maybe, seven to eight games a year. That’s a part of it,” Martinez said. “It’s up to us as hitters to find out what we’re doing that day, because everything changes.”

DH OUTLOOK

Primary 2019 starter: J.D. Martinez

Projected 2020 starter: Martinez

Major league depth: Michael Chavis, Rafael Devers, Bobby Dalbec.

Prospect to watch: Dalbec.