MLB

OFFENSE STRUGGLES AGAIN

Moises Alou slammed his bat down in impotent fury in the fifth inning, first called out by umpire Dana DeMuth then tossed out for his tantrum. It was the signature image of last night’s 5-3 loss to Washington, and it perfectly captured the Mets’ offensive struggles – and perhaps the mounting frustration going with them.

Aaron Heilman’s meltdown notwithstanding, the Mets have pitched well enough to win, but hit poorly enough to lose, especially in the clutch.

“When you get clutch hitting, the outcome is going to be better,” Carlos Delgado said. “It’s probably the hardest thing to do in all of sports, though.”

It clearly has been for the Mets. Their .375 slugging percentage was just 24th in the majors. And in close situations late in games, their .218 average was next to last in the league and their .246 slugging percentage next to last in the majors.

Small wonder frustrations may have boiled over last night, as they saw Tim Redding hold them to a run and two hits over six innings.

Alou has helped the offense, which averaged 5.7 runs in his first eight games back after mustering just 4.5 in the 29 games without him. But when he got caught looking at Redding’s 2-2 pitch in the fifth, he smashed his bat across home plate and got ejected, and was long gone before the clubhouse opened.

“I think slamming his bat did it more than anything,” manager Willie Randolph said. “Obviously the guy’s frustrated. (DeMuth) said he said the magic word. I don’t know if he said it before he slammed the bat or after, but when you do something like that, it was a little violent, the umpire didn’t like it I guess.”

The Mets scored lone runs in the seventh and eighth to make the score look more palatable. But their 183 runs coming in were 10th in the NL. Unless they get this sputtering offense in gear, it could prove the Achilles’ heel that dooms their October dreams.

brian.lewis@nypost.com