Mike Celizic

The Giants did a lot of good things against Dallas Sunday in a game that goes a long way toward deciding the NFC East. Eli Manning threw with confidence and accuracy. The defense finally resembled the hard-hitting unit that began the season. Tiki Barber and the running game were terrific. Jeremy Shockey was a big piece of the offense.

But New York didn’t win what was the equivalent of a playoff game. They had it in their hands and dropped it, done in not by lack of effort or inferior talent, but by mistakes and undisciplined play.

The Cowboys get all the same props for playing with purpose and intensity. Martin Gramatica, who hasn’t kicked in a regular-season game in more than a year, was a hero. Tony Romo wrote another chapter in what shows signs of becoming a legendary story.

Unlike the Giants, the Cowboys didn’t beat themselves. Unlike the Giants, they rose to one of the regular season’s biggest challenges. In a mediocre division in the stretch run of a season without greatness, Dallas seized its moment.

It’s been a great turnaround for Big D, which started the season poorly behind the mobility-challenged Drew Bledsoe and has turned everything around with the installation of Romo at quarterback. When Bill Parcells made the switch, I had thought it was too late to save the season, but Romo needed virtually no breaking in. He was good from the get-go and has turned the Cowboys into a team that has to be considered a favorite to win the NFC; Seattle looks to be the co-favorite, with the Bears too weak at quarterback to have anything other than an outside shot.

The Giants have experienced a turnaround just as dramatic as that of the Cowboys, except in the other direction. They began the season looking like one of the two best teams in the NFC. Injuries crippled them, but they’ve done at least as much damage to themselves.

On Sunday, the division was there for them, and they gave it away. Instead of being tied with Dallas, they’re two games back, tied with Atlanta for the final wild-card spot.

There are five games remaining, and Dallas has pretty much locked up the division, thanks to the Giants.

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The role of coach Tom Coughlin in this collapse has been well-documented. He’s a stickler for detail, like arriving 10 minutes early for meetings and keeping both feet planted on the floor when the meetings start. But on the field, his team is as disciplined as a boxful of puppies.

Sunday, the Giants committed four personal fouls, three of which were blatant late hits. Plaxico Burress, the team’s lead knucklehead, was responsible for one of them. Another came on an out-of-bounds hit that helped Dallas go ahead late in the game.

They also were guilty of an enormous defensive breakdown. After Manning and Barber led them to the tying touchdown with just over a minute left, the Giants defense gave up a 42-yard pass completion to get the Cowboys into instant winning-field-goal range. If the pass had gone to one of Dallas’ premier wide-outs, Aaron Glenn or Terrell Owens, on a great individual effort, you might tip your hat with grudging respect to the other guys. But this was to Jason Witten, the tight end, for pete’s sake. Unforgiveable.

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Sunday’s showdown — at home — for the division lead against an ancient division rival was the sort of game that championship teams win, the stuff that launches teams to the Super Bowl. The Cowboys passed the test, which shouldn’t be surprising; Parcells’ teams are famous for saving their best football for the final month of the season.

The Giants failed. Given the way they’ve played for three years under Coughlin, their performance shouldn’t be surprising, either.

You don’t win titles by taking dumb penalties. You don’t win by blowing coverages in the most critical moments in the game.

If this game had been at the beginning of the season, the Giants could have looked at all the good things they did and taken heart from it. But it’s December now, and the schedule is running low on games. It’s not the time for moral victories or being proud of all the things you did right.

Right now is the time when teams’ fitness for the postseason is put to the test. The Cowboys passed this exam; the Giants failed.

New York may yet make the playoffs. It’s not as if the other contenders are without flaws. But they’re not headed to the Super Bowl. Not playing the way the did against Dallas on Sunday. Not giving games away.

NFL game stories Quick look at Week 4 games STEELERS 23, RAVENS 20, OT: Baltimore loses first game of season REDSKINS 26, COWBOYS 24: Dallas can't contain Portis in 1st loss BEARS 24, EAGLES 20: Goal-line stand boosts Chicago JETS 56, CARDINALS 35: Favre throws career-high 6 TDs BUCS 30, PACKERS 21: Ryan's 3 FGs lift Tampa CHARGERS 28, RAIDERS 18: San Diego tops rival 10th straight time BILLS 31, RAMS 14: Buffalo 4-0 for first time since 1992 CHIEFS 33, BRONCOS 19: Johnson rushes for 198 yards for K.C. BROWNS 20, BENGALS 12: Anderson throws TD TITANS 30, VIKINGS 17: Tennessee 4-0 for first time ever PANTHERS 24, FALCONS 9: Smith honors Lucas after TD JAGUARS 30, TEXANS 27, OT: Scobey kicks game winner SAINTS 31, 49ERS 17: McAlister scores first TD of year