MLB

Rauch gives up crucial homer in loss; has ‘tender’ elbow

TAKEOUT CARD: Adron Chambers’ slide prevents Daniel Murphy from completing a double play in the seventh inning of the Cardinals’ sweep-avoiding win over the Mets. (Neil Miller)

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Just imagine what the Mets might be if they had even a mediocre bullpen.

A bad situation seems destined to get worse before it improves: Jon Rauch is the latest reliever hurting, putting an already thin bullpen on the verge of depletion.

After Rauch surrendered a two-run homer to Allen Craig in the eighth inning of the Mets’ 5-4 loss to the Cardinals yesterday, the right-hander was headed to the Hospital for Special Surgery to have his elbow examined.

BOX SCORE

Manager Terry Collins said Rauch told him he has been experiencing intermittent “tenderness” lately in the elbow, with the latest flare-up occurring as he prepared to enter yesterday’s game.

With the score 3-3, Rauch entered and allowed a leadoff single to Matt Holliday before Craig homered over the left-field fence with one out, helping deny the Mets a four-game sweep against the defending World Series champions.

Rauch’s barking elbow caught the Mets by surprise.

“His velocity was right there where it normally is and everything else seemed solid,” catcher Mike Nickeas said. “So there was no reason for me to think anything was wrong. It wasn’t until afterward that I found out.”

Flushed was a solid start from Dillon Gee, who allowed three runs (two earned) on six hits over seven innings with eight strikeouts and two walks.

Rauch and Ramon Ramirez (hamstring) are both disabled-list candidates, potentially leaving the Mets to dig deeper into the minor leagues for relief help as they prepare to open a three-game series tonight at first-place Washington.

Rauch’s latest implosion boosted the bullpen’s ERA to 5.45, worst in the major leagues. But the Mets (31-24) aren’t deterred. They finished the homestand 7-4 with the bullpen woes playing a major role in three of the losses.

On the flip side, Johan Santana pitched the first no-hitter in franchise history on Friday and R.A. Dickey also is on a roll.

“We’ve been playing great, and hopefully we can continue with a big series coming up in Washington,” Lucas Duda said. “We’ve pitched well. We’ve just got to stay positive and keep on battling.”

Scott Hairston’s pinch-hit, two-run homer against Marc Rzepczynski in the seventh gave the Mets new life after the Cardinals had taken a 3-1 lead in the top of the inning.

Gee was responsible for the biggest gaffe, a throwing error to second base on Daniel Descalso’s comebacker, allowing the Cardinals to take a 2-1 lead. Rafael Furcal’s RBI fielder’s choice later in the inning added another run.

“Today we win the game if we execute a couple of plays,” Collins said. “We’ve got to play better.”

Dudaism was alive and well in the fourth, when Duda’s solo shot, his fifth home run of the homestand, made it 1-1. The blast was Duda’s ninth of the season, extending his team lead.

“He’s getting the bat out front much better than he was,” Collins said. “So once in a while you can over-swing. But right now he’s getting in position to hit, he’s getting the bat out front, so he should be getting some balls to drive.”

Duda said the Mets had nothing to be disappointed about.

“That’s a good team — a real good team out there,” he said. “Three out of four from that team is real good.”

mpuma@nypost.com