MLB

K-Rod, Isringhausen close out another Mets win

The Mets’ infield looks like an Abbott and Costello joke. Their starting rotation has more question marks than the Riddler and their best performing hitter this season likely won’t be in Queens to finish it.

It’s amazing to think, after their horrendous start, the Mets (20-22) are two games under .500 and have turned their biggest weakness, their bullpen, into their biggest asset.

Following Jon Niese’s seven shutout innings in the Mets’ 3-0 win over the Nationals at Citi Field last night, Jason Isringhausen and Francisco Rodriguez tag-teamed once again to preserve the lead in the eighth and ninth innings.

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“Unbelievable,” manager Terry Collins said of his relievers. “Those two guys absolutely are fearless. They come in any situation and just on savvy and experience, make pitches.”

“That’s what we were hoping,” Isringhausen said of the duo’s solid start to the season. “It’s fun. I don’t take anything for granted. I go out and take it one day at a time. I know, it’s happened to me before, one pitch it can end all again. I’m old and my body aches, but they know that and I know that, but it’s not going to stop me.”

Isringhausen, 38, lowered his ERA to 1.93 and is tied for second in holds in the National League with 10, and Rodriguez dropped his ERA to 0.83, earning his 13th save of the season after forcing the Nationals into two easy fly balls with runners on first and second.

Isringhausen has not allowed a run in his past seven appearances, and it has helped him to have a guy behind him who has pitched 17 consecutive scoreless innings.

“You got a guy like [Rodriguez] coming in behind you, you don’t worry as much,” Isringhausen said.

With the return of rookie Pedro Beato from the disabled list, the Mets could be back to shortening games to six innings. Beato hasn’t allowed an earned run over the first 17 innings of his major league career and is on the verge of breaking the franchise record, held by Jack DiLauro, who did not allow an earned run in the first 17 2/3 innings of his career in 1969.

Beato will return to his seventh-inning duties as a bridge to Isringhausen and Rodriguez, a role he has embraced. As the warmup act for the two veteran closers, Beato is soaking up everything he can.

“I speak to them every day,” Beato said. “Any little thing that comes up I can ask them about and it helps me in the long run. There’s no reason why I shouldn’t pick their brains.”

howard.kussoy@nypost.com