MLB

Parnell flops as Marlins beat Mets again

MIAMI — A dead-fish slider produced the opposite effect in the eighth inning yesterday at Sun Life Stadium: The Fish were alive. The Mets were on their way to dead.

Just chalk it up as part of Bobby Parnell’s growing pains as he tries to prove his fitness as the Mets’ closer of the future.

“The guys battled their butts off today, and to make a stupid decision to hurt the team, it really [stinks],” Parnell said after Logan Morrison’s homer leading off the Marlins’ eighth sparked a two-run inning and 5-4 loss for the Mets. “It was the wrong pitch in the wrong situation.”

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Parnell, who usually flirts with triple digits on the radar gun, said he wanted to bounce a 2-2 slider at Morrison’s feet. Instead, the pitch hung, and Morrison crushed it over the center-field fence.

John Buck’s RBI double later in the inning gave the Marlins the go-ahead run and sent the Mets away having lost six of 10 games since the All-Star break.

The Mets were in good shape after David Wright’s two-run homer in the seventh against Anibal Sanchez gave them a 4-3 lead. Wright finished the game with three hits — he was 6-for-14 (.429) with six RBIs in the three-game series after returning from the disabled list — but the Mets were only 1-for-9 with runners in scoring position.

“I didn’t want to come to this team and be a guy that wasn’t ready, and hurt those guys,” Wright said. “It’s tough to pat yourself on the back after you just lost two of three [games].”

The Mets (50-51) open a four-game series in Cincinnati tonight before going to Washington for three games. By the time they arrive home at Citi Field, they figure to be without Carlos Beltran, who remains on the trade block, and they could be done in the wild-card race. They are 8½ games behind the Braves, who lead the wild-card standings.

“We’ve got a tough trip to Cincinnati — we’ve got to go in and win three there and get back on track,” manager Terry Collins said.

Dillon Gee struggled to survive five innings, in which he surrendered three earned runs on seven hits with three walks and three strikeouts. The right-hander allowed a run in the first inning before Mike Stanton’s homer leading off the second gave the Marlins a 2-1 lead. Emilio Bonifacio added another run with an RBI single later in the inning.

Gee put at least two runners on base in each of his five innings. The Mets didn’t get any stability until Manny Acosta entered to pitch two perfect innings of relief.

“I literally felt like I was in a dogfight out there, and I was just fighting myself the whole time,” Gee said. “I just didn’t get things started in the right way. I just didn’t limit the damage and keep us in the game.”

Beltran’s sacrifice fly in the first gave the Mets a 1-0 lead. In the sixth, Jason Bay delivered an RBI single that pulled the Mets within 3-2 before Wright put the team ahead with his homer an inning later.

And then Parnell was greeted by Morrison’s bomb.

“[Parnell] has got to bounce back from this,” Collins said. “He’s very upset and mad at himself. But you’ve got to pick up the pieces and get ready for [tonight].”

mpuma@nypost.com