ST. LOUIS -- The line separating reasons and excuses often is thinly drawn. And sometimes excuses are disguised as reasons. Who can determine what's what?

Paul Lo Duca watched all of the Mets' 6-3 loss to the Cardinals on Thursday and said, "We were due for one." He thought what he witnessed was a day game that had been preceded by a night game, and he based that evaluation on what he saw, not the schedule.

His manager wasn't sure why the Mets had appeared worn down. He didn't dismiss fatigue as a factor, nor did he accept it.

"You know," Willie Randolph said, "[winning pitcher] Jason Marquis threw pretty well today."

And so perhaps the issue wasn't how tired the Mets were, but how effective Marquis was. Or how ineffective the Mets' bats were. Tim McCarver once pointed out that Bob Gibson not only was a great pitcher but also an exceptionally smart one. "He always pitches," McCarver said, "when the other team doesn't hit." Maybe that's all Marquis did.

Whatever the reason/excuse/deduction, the Mets were not much of a match for the Cardinals on Thursday. They lost for the sixth time during their nine-game excursion to Philadelphia, Milwaukee and the banks of the Mississippi. They lost for the seventh time in 10 games. And make no mistake, this was at least as much a Mets loss as it was a Cardinals victory. The home team played without Albert Pujols; the Mets played without the level of energy that they have demonstrated in most of their 40 games.

His rest over, Pujols will play on Friday. Their homeless stretch over -- the Mets have been on the road for 20 of the last 27 days -- they will play the Yankees on Friday. And Saturday and Sunday. "It can't hurt," one of them said. "We need to get re-charged."

And they need to get more from their pitching. Losing pitcher Jose Lima didn't pick the right day to face the Cardinals. It was the day they produced six runs and eight hits and exploited the Mets' flawed defense, the day David Eckstein had three hits and two RBIs, the day Scott Spiezio disguised himself as Pujols -- Spiezio cleverly wore a first baseman's glove -- and drove in two runs.

Lima lost for the third time in three starts since his promotion from the Minor Leagues and was unable to reach the sixth inning for the third time. He allowed five runs, four earned, in 4 2/3 innings. Four of the runs, including the one his error made unearned, scored in the first two innings.

His place in the rotation, however, appears no more precarious as a result, because Brian Bannister, who probably would have displaced Lima next week, felt tightness in his problematic hamstring on Thursday and now is unlikely to return as soon as the Mets had anticipated.

The Mets' offensive shortfall made Lima's ineffective work somewhat inconsequential. A two-run home run by Carlos Beltran, a bases-empty home run by Jose Valentin and two singles by Carlos Delgado constituted the full extent of the Mets' production in 7 2/3 innings against Marquis (5-4). Their only other hit was the well-struck but misjudged fly ball Cliff Floyd hit off Jason Isringhausen, who brushed it off and notched his 13th save of the season. It was a double that advanced David Wright to third base and produced the game's lone moments of drama -- Ramon Castro and Endy Chavez batting with chances to tie the score against the Cardinals' closer.

Beltran had hit his 10th home run in the fourth inning, and Valentin, Marquis' final batter, hit his second home run in the eighth. Marquis walked three and struck out two.

"We'll just go home and regroup," Randolph said.

The Mets have played well at Shea. But they played well on the road until this trip, and now they face the Yankees and Phillies.

Their performance Thursday was defensively flawed. Lima, covering first base on a ground ball Delgado handled in the second inning, lost Delgado's throw in the backdrop of a white Bank of America sign. Eckstein scored from second base on what could have been the third out. Lima might have escaped allowing one, rather than two, runs in an inning earlier as well. But Beltran made an ill-conceived and conspicuously late throw to the plate on a run-scoring single by Scott Rolen that allowed Rolen to reach second base. A single two batters later by Spiezio scored Rolen.

"That's part of the game," Randolph said in absolving his center fielder.

And Randolph characterized Lima's performance as "a pretty good job."

Lima thought his command was improved over what it had been. He thought he got blooped twice. His teammates recalled one instance -- maybe.

"One pitch here, one pitch there," he said.

He lamented the three two-out runs he allowed.

"But no excuses," he said.

Those were reasons.