PHILADELPHIA -- There was the image of Carlos Beltran in the second inning of Sunday's game, twisting his body in both directions before smashing unknowingly into the center-field wall. There was the image of Beltran one inning later, unsuccessfully fielding Jayson Werth's RBI double. Then there were the snapshots of Beltran striking out in three consecutive at-bats, twice stalling critical rallies for the Mets.

So it went for Beltran in his most frustrating game of the season, a 6-5 loss to the Phillies that, like so many before it, had the potential to become an uplifting victory. Instead, Beltran left the Mets scratching their heads, unsure of just when -- or if -- their All-Star center fielder will once again be able to help the team.

"I wish I could have better results," Beltran said. "But right now nothing good is happening."

Beltran's season reached its lowest point to date in the seventh inning, with the tying run on second and Phillies starter Roy Halladay no longer throwing his trademark wicked pitches. Working his way into a hitter's count, Beltran fouled off a cutter and a changeup before swinging through a 79-mph curve.

An inning earlier, Beltran struck out with a man in scoring position, unable to advance Angel Pagan to third base with no outs.

But perhaps most frustrating for Beltran was Werth's home run in the second. After starter R.A. Dickey retired the first four batters of the game, Werth sent what initially appeared to be a routine fly ball to straightaway center. Running sideways, Beltran turned first in one direction, then in another, until he slammed unknowingly into the wall. Werth's hit cleared the fence by inches.

It would have been a difficult play and a fantastic catch -- but one that the Beltran of old used to make with apparent ease.

"As he started drifting back and drifting back, I thought he might have a shot," Dickey said.

"I would have caught it if I didn't get stuck in the fence," Beltran said. "I would have caught it."

But he didn't, and the Phillies instead took the lead. An inning later, Raul Ibanez hit a thunderous three-run homer to give the Phillies a four-run cushion. And despite the best efforts of Pagan, Jose Reyes, Chris Carter and Josh Thole -- all of whom contributed to a series of late rallies against an uncharacteristically shaky Halladay -- the Mets could not claw their way all the way back.

"It's a little easier to sleep at night taking a win out of it," Halladay said.

And perhaps a bit more difficult for Beltran to sleep.

Throughout the first half of this season, the Mets waited patiently for their injured center fielder, playing mostly stellar baseball but always knowing that help was on its way. General manager Omar Minaya likened Beltran's return to acquiring an All-Star slugger at the Trade Deadline. The Mets likened it to funneling in a heavy dose of jet fuel.

But Beltran has not played even remotely like an All-Star in his four weeks with the club. He has struggled to make accurate reads in the outfield, despite feeling no ill effects from his offseason knee surgery. And he has descended into a massive funk at the plate, finishing 3-for-22 against the Phillies and Braves to drop his average, to .195. He has six extra-base hits in 77 at-bats.

"He's battling really hard to get it done," said Pagan, who filled in admirably for Beltran. "It's just not happening for him right now. But believe me, whenever he gets hot, he'll be hot. We're not worried about that."

That's been the company line throughout Beltran's period of struggle. But it's no secret that Beltran's presence, however comforting, has affected them adversely. Because Beltran lobbied to remain in Sunday's lineup, manager Jerry Manuel could not pencil the streaking Jeff Francoeur's name onto the card. And because Beltran struggled in the field and at the plate, the Mets were unable to make good on both their late rallies and early efforts.

Certainly, Beltran is not the only reason the Mets lost on Sunday. Dickey allowed a season-high six runs in a season-low three innings. David Wright struck out three times, finishing 2-for-23 on the team's critical six-game road trip.

But Beltran's mistakes stood out in light of his recent struggles. The Mets have to play him, because he'll never regain his form if they don't. But they must balance that need for playing time with a growing urgency to win.

"It's just a matter of getting out there," Manuel said. "He'll have to make some different adjustments."

For the Mets to have any chance of closing a season-high nine-game deficit in the National League East, they need Beltran to produce. They know that. He knows that. But he's running out of time.

"It will come," Beltran said. "It's hard, because I know that if I do better, I can help the team. But at the same time, no one is working harder than myself. I'm doing everything I can."