Mets pitcher Shintaro Fujinami throws during a spring training workout...

Mets pitcher Shintaro Fujinami throws during a spring training workout on Feb. 17 in Port St. Lucie, Fla. Credit: Newsday/Alejandra Villa Loarca

JUPITER, Fla. — Shintaro Fujinami is a 6-6, 180-pound stringbean of a reliever. He regularly touches 100 mph with his fastball, which he mixes with a dangerous splitter. And as a rookie last year, he had a 7.18 ERA and one of the worst walk rates in the majors.

The Mets deemed that combination — seemingly excellent pitches, terrible results — absolutely worth a shot. Maybe they can help him figure it out.

That is why the 29-year-old Japanese righthander is in spring training on a one-year, $3.35 million contract, trying to win one of the few bullpen spots available in the leadup to Opening Day.

What is his potential? What can he be if the Mets harness that electricity?

“All-Star closer,” pitching coach Jeremy Hefner told Newsday on Saturday. “The stuff is real. It’s all about strike-throwing and getting into advantage counts and getting him in positions to have success and seeing that success. But the stuff is real.”

Fujinami hasn’t appeared in any exhibition games because of a weird start to camp. Initially, his work visa prevented him from fully, officially participating in team activities. Then he had to return to Japan to tend to a personal matter (a trip during which he resolved the visa issue).

On Saturday, he returned. He said he expects to get into a Grapefruit League game “shortly”; manager Carlos Mendoza indicated it could be as soon as within a few days.

Then the Mets can get to trying to unlock that tantalizing potential.

“We’re playing the long game with him,” Hefner said. “With these types of talents, you want to spend all the energy you possibly can to try to help them figure it out.”

It’s the long game in the sense that the start of the season isn’t any sort of deadline. Fujinami can be optioned to the minors, which would allow him to continue to experiment in a lower-stress environment. But Fujinami will be a free agent after this season, so the Mets hope he becomes a contributor soon.

“We want that adjustment to be fast,” Hefner said. “But ultimately, we’re along for the ride.”

Two clubs already have tried what the Mets are attempting. Coming to the majors after pitching professionally in Japan for a decade, Fujinami opened last year with Oakland, which allowed him to try to be a starter. It went poorly, so the A’s put him in the bullpen. In July, he was traded to Baltimore.

As bad as Fujinami’s numbers look, he did show significant improvement over the course of the season.

In the first half, he had a 9.00 ERA and 1.76 WHIP, which was untenable. In the second half, he had a 4.76 ERA and 1.15 WHIP. July was his best month.

“The biggest thing is that I attacked the zone more toward the end of last year,” Fujinami said through an interpreter. “I got better toward the end of the time in Oakland, not the time I moved to Baltimore. So I’m gradually getting better and throwing more strikes.”

He walked 12.6% of his batters faced — about one out of every eight. That is a lot. His walk rate ranked 19th out of 357 pitchers who tossed at least 50 innings.

Along the way, Fujinami’s fastball averaged — averaged — 98.4 mph. He threw five pitches overall, but the second-best option was the splitter. His version is harder than Kodai Senga’s (93 mph versus 83 mph) and doesn’t move as much.

Senga and Fujinami are countrymen, locker neighbors and former World Baseball Classic teammates. But they had very different experiences in their stateside debuts, with Senga finishing second in the National League Rookie of the Year voting.

The key to Fujinami getting better, Hefner said, is to just keep pitching.

“It’s experiential at this point,” he said. “He’s got to layer on some experience. Senga’s adjustment was so fast and he handled everything so well. But that’s not everyone’s story. So Fuji is creating his own story.”

SHINTARO FUJINAMI BIO BOX

Age: 29

Throws: righthanded

Height, weight: 6-6, 180

Contract: one year, $3.35 million

2023 stats: 7.18 ERA, 1.49 WHIP, 98 mph fastball

NPB stats: 3.41 ERA, 1.35 WHIP in 10 seasons

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