But in crafting the biggest win of his Cowboys tenure on the strength of his defense, he exposed the shortcomings that have been building in New Orleans for a least a month and could make the Saints vulnerable in the playoffs. The Saints have scored 40 or more points four times this season, but they have turned into slow starters — they went three-and-out on their first two drives, were down by 14-0 to the Cowboys after less than 10 minutes and managed just a field goal in the first half — which means their offense becomes one-dimensional. “When they throw that many times, they’ll get yards,” Phillips said. “You’ve got to keep them out of the end zone.”

The Cowboys were then able to do what they wanted: play deep, rush the passer, allow Brees to cherry-pick the short and medium pass patterns. It was nothing new — surely Bill Belichick would have liked to get that kind of pressure on Brees, too. But with DeMarcus Ware, who was taken off the field on a back board last week and playing only on passing down to preserve his energy, the Cowboys put more pressure on Brees than he had faced all season. With Jeremy Shockey injured, the Saints could not use a two tight-end set to protect Brees, who was sacked four times, fumbled twice and was sent running for his life throughout the night.

The Saints’ offensive line looked like a liability, with left tackle Jermon Bushrod leaving his quarterback’s blind side so exposed on one sack that the entire Superdome gasped as it saw Anthony Spencer closing in on a clueless Brees.

The end result: the Saints had just three plays of more than 20 yards — the 35-yard pass play Brees is credited for was actually a short pass and long run by Marques Colston — a remarkable statistic considering that against the Patriots less than a month ago, Brees averaged 20 yards per pass play. Against the Cowboys, it was just half that. According to an unofficial tally, Brees did not complete one of the six deep passes he attempted Saturday night. And if one play foretold disaster it was Brees’s deep attempt down the left sideline intended for Devery Henderson. On a normal night, that would have been a 41-yard touchdown pass. Instead, it was a red-zone interception at the 4-yard-line.

“It was one of those nights we weren’t quite clicking,” Brees said. “When you’re throwing the ball every play, they can pin their ears back and rush. They did a good job of staying back and not allowing big plays. We didn’t do a good job of taking the underneath stuff.”

It did not help that Brees was without one of his security blankets — Shockey (turf toe) all night — and without another, running back Reggie Bush (pulled up with what appeared to be a hamstring injury) for the second half. Their absence was especially glaring because the Saints could not sustain drives, going 1 of 7 on third down. That certainly does not give a quarterback time to establish a rhythm, and it does not give a break to an injury-depleted defense that was being shredded by the Cowboys. The Saints held the ball for 13 fewer minutes than the Cowboys, an eternity when the offense has the Saints’ big-play ability.

“We need to get back to scoring fast,” Brees said.

All of that is correctable — the Saints will get plenty of players back from injury for the playoffs, if not sooner — and their defense should hark back to the aggressive unit it was in the first half of the season. Late on Saturday night, Brees was disappointed that the quest for perfection had ended because he wondered how many times a team could get that close to history. But in the locker room, the page had already turned.

“It became a short-term goal,” linebacker Scott Shanle said. “We have the long-term goal out there. Maybe the whole focus can shift to getting home-field advantage.”

On a night when their big play game disappeared, the Saints were finally able to take the long view.