PORT ST. LUCIE, Fla. -- The Mets’ acquisition of Darin Ruf last August, general manager Billy Eppler said Monday, “was a trade that didn’t work out -- plain and simple.” Over two months in New York plus another six weeks this spring, Ruf didn’t perform anything like his track record as a righty masher suggested he might.

Rather than attempt to wring additional value out of that mistake, Eppler officially moved on from it Monday by designating Ruf for assignment. The move cleared the Mets to carry speedy fifth outfielder Tim Locastro on their Opening Day roster, giving manager Buck Showalter the flexibility to manage games in more creative ways.

“Just like last year on some things, we’re going to make the best baseball decision we have to make,” Eppler said.

Eppler executed the move with approval of owner Steve Cohen, who signed off on the Mets eating the additional $3.25 million owed to Ruf -- much as he did last year in designating Robinson Canó for assignment despite approximately $37.5 million remaining on his contract.

The move was made in hopes of creating a greater diversity of talent on the Mets’ bench, which will include Tommy Pham, Luis Guillorme, Tomás Nido and Locastro. Even if Ruf had performed well in spring, his skill set would have overlapped with that of Pham, another right-handed-hitting outfielder who can platoon with Daniel Vogelbach at DH.

“You don’t want to be holding a three-run lead and then look down your bench and everybody’s just a big hairy guy that hits the ball in the seats,” Eppler said.

Locastro, who has stolen 39 bases in 44 attempts over a six-year big league career, offers a different element -- one the Mets can emphasize given Major League Baseball’s new rules to encourage base stealing, such as larger bases and a limit on pickoff throws. This spring, Locastro went 6-for-6 on steal attempts with a .907 OPS at the plate. He rates among the fastest 1% of players in the league, according to Statcast data from the past four years.

“[They told me] just be ready to go, ready to steal some bases and help the team win,” Locastro said. “That’s been sort of my M.O. my whole career.”

Locastro’s achievement almost certainly spells the end of Ruf’s Mets career, following a spring that saw him receive a cortisone injection to relieve arthritic symptoms in his right wrist, then bat .167/.265/.233 over 11 Grapefruit League games. Although Ruf performed well on the back fields, according to Showalter, it was not enough to save him given his wider struggles since joining the Mets.

After coming to the Mets in a trade with the Giants last August, the 36-year-old Ruf hit just .152/.216/.197 without a home run. The team gave up four players to get him, including J.D. Davis, who produced an .857 OPS after the trade, and prospect Thomas Szapucki, who posted a 1.98 ERA as a reliever.

Any team that claims Ruf on waivers will be on the hook for the entire $3.25 million remaining on his contract. If Ruf clears waivers -- a more likely scenario given his struggles -- he can refuse an outright assignment to the Minors and elect free agency. In that case, a signing team would pay him the minimum Major League salary of $720,000, with the Mets picking up the other $2.53 million.

“It was probably one of the toughest conversations I’ve had here,” Showalter said of the decision. “Somebody is going to get a guy that can help them.”

The Mets broke camp on Monday needing to make one additional move to shave their roster down to 26 players, which they will do by Thursday morning. They are likely to option pitcher Elieser Hernandez to Triple-A Syracuse, where he will serve as starting-pitching depth.