New York Mets designated hitter Darin Ruf at spring training last...

New York Mets designated hitter Darin Ruf at spring training last month. Credit: Newsday/Alejandra Villa Loarca

PORT ST. LUCIE, Fla. — Admitting defeat on one of the worst trades in their recent history, the Mets cut Darin Ruf on Monday to make room for Tim Locastro, opting for elite speed over theoretical thump for the last bench spot on their season-opening roster.

Locastro, a backup outfielder who will be the Mets’ top pinch-running option and stolen-base threat, won a job with a standout camp after signing a minor-league contract in January. Ruf, a DH/first baseman/occasional outfielder, entered the spring looking like a lock to stay on the team, but his continued struggles — after a terrible two months with the Mets last year — introduced intrigue that lasted till the final day of spring training.

Buck Showalter said dumping Ruf, 36, was “probably one of the toughest conversations I’ve had” in his year-plus as Mets manager.

Unless he ends up on another club via trade or waiver claim, the Mets will owe Ruf $3.25 million.

“I feel bad for him as a person,” general manager Billy Eppler said. “It was a trade that didn’t work out. Plain and simple.”

Showalter said: “We did what was best for the Mets. And in the long run, I think it’ll be what’s best for Darin too.”

Ruf’s miserable Mets tenure began on Aug. 2, when the Mets acquired him from the Giants at the trade deadline for J.D. Davis and three minor-league pitchers. It ended after his 0-for-3 effort Sunday dropped his Grapefruit League average to .167 and OPS to .498.

The Mets added him as a replacement for Davis, a DH against lefthanded pitchers. At the time, Davis was struggling and Ruf was fine as a regular player for San Francisco. But a switch flipped almost immediately after they swapped sides, with Ruf flailing in his part-time role and Davis, 29, shining with the Giants.

Davis, a younger player with a similar skill set, hit eight home runs with the Giants. Ruf had 10 hits and zero homers with the Mets. He played so poorly that the Mets called up prospects Mark Vientos and Francisco Alvarez to see if they could do better.

“It was hard for him to get his feet underneath him,” Eppler said.

The roster ramifications of Ruf’s departure include leftfielder Mark Canha becoming the backup first baseman, plus an opening in DH playing time against lefthanders. Tommy Pham, also a backup outfielder, likely will be in the lineup with a lefty on the mound, though the Mets could use that spot to give other position players a day off defensively. Daniel Vogelbach will play against righties.

The other piece of this transaction: The Mets like the 30-year-old Locastro, who is able to play all three outfield spots. Eppler said he especially values Locastro’s ability to steal bases since MLB implemented certain steals-friendly rules, including slightly bigger bases and pitchers being limited to two pickoff attempts per plate appearance.

“We’re kind of making a little bit of a bet on the stolen-base element,” Eppler said. “One of the things we looked at analytically over the weekend was how often do situations happen in the sixth, seventh, eighth, ninth inning where somebody that we might pinch run for would get on first base with second base open. Being able to give Buck that bullet to fire as he sees fit, we just felt that that was important.”

Eppler also mentioned “the diversity of the bench.”

“You don’t want to be holding a three-run lead and then look down your bench and everybody is just a big hairy guy that hits the ball in the seats, right?” he said. “You want to have somebody that can defend.”

In addition to hitting .289 with a .907 OPS, Locastro stole six bases in six tries during spring training.

“He had a skill that he wanted to show,” Showalter said. “He did everything he could do to win a job down here. And he did.”

But Locastro also has a .227 average and .656 OPS in parts of six seasons with the Dodgers, Diamondbacks and Yankees. The Mets don’t intend to rely on his hitting abilities.

Team officials told Locastro he made the club Sunday night.

“I walked in [to that meeting] and it was 50-50 in my eyes. Fortunately, it went my way,” Locastro said. “[Showalter said] be ready to go, be ready to steal some bases and help the team win. That’s been my MO my whole career.”

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