ARLINGTON, Texas - The case against Donovan McNabb was made most convincingly here last night by Donovan McNabb.

He didn't complete a pass until midway through the second quarter.

One of his biggest gains came when he threw an interception and the Eagles got the ball back downfield on a fumble recovery.

For the Eagles' best offensive play, a 76-yard touchdown catch by Jeremy Maclin, McNabb was on the sideline.

It was a very bad night for the franchise quarterback of 11 years, and a very rough night for anyone inclined to defend him from the detractors who blame him for every season-ending Eagles loss. A consensus of mysterious origin had formed in the public discourse that McNabb needed a strong postseason performance against the Dallas Cowboys in order to hold on to his job beyond this year.

Let's all agree that was not a strong performance. The offensive line was horrible, the coaches' scheme was disastrous, the play calling was not particularly good. McNabb didn't have much of a chance. But even with all that, he wasn't good enough.

For the Eagles to win this game, he had to be.

So now what?

If McNabb's final game as an Eagle turned out to be a blowout playoff loss in Dallas, he'd be in good company. We have seen this very game before. Twice. And both times, an era ended with the final gun.

After the 1992 season, the Eagles were blown away, 34-10, by a young Dallas team on its way to the first of three Super Bowl championships in the 1990s. The Eagles were never in the game. Reggie White never played for them again.

After the 1995 season, the score was 30-11. Randall Cunningham's run as an Eagle ended that day. After 11 seasons, incidentally.

McNabb has one more year on his contract after agreeing to renegotiated terms without an extension last year. That is one of the reasons for the speculation about his future. With Kevin Kolb in development, the Eagles seemed to be giving McNabb a year to prove he could remain healthy and carry the team through another playoff run.

They could extend his contract after this. They could keep him for 2010 and let him leave as a free agent. They could keep him and then place the franchise tag on him after next season (assuming there is a franchise tag in the new contract with the players' union).

Or the Eagles could attempt to trade McNabb, turn the team over to Kolb, and see what happens. Most of their energy in free agency and the draft should be on fixing the defense, so it might not be a bad time for a transition on offense.

What the Eagles will do is unknown. What they should do is a different matter.

McNabb is one of the very best players in the history of this franchise. For as long as there are Eagles fans, there will be debate about his career. There will always be those who think he was fatally flawed and those who believe he was simply asked to carry too heavy a load for too long.

In the end, the man who will judge his case has some issues of his own. Andy Reid may look at this as a chance to untether himself from his very first draft choice and see how his offense works with a new QB. But Reid would have to do so knowing that he deserves a lot more blame for last night's mess than McNabb did.

This Eagles team fell apart along the cracks that were there from the beginning. Reid spent a lot of money on Shawn Andrews, Jason Peters and Stacey Andrews to anchor the offensive line. That line failed miserably in consecutive blowout losses to the Cowboys.

The defense took a blow when middle linebacker Stewart Bradley tore up his knee during training camp. But the most glaring issues were the dreadful tackling and the bad personnel decisions at safety. Quintin Demps and Sean Jones were not the answers.

The Michael Vick thing never made sense. Never. Not on the field or off.

Once the sting wears off and reason takes over, Reid should extend McNabb's contract for three more years and let him continue to work with the array of weapons that developed so thrillingly during the regular season. Fix the line and the defense and the Eagles can compete in an even tougher NFC East next year.

There is a very real chance that Reid will go the other way, that the coach will offer up his quarterback as a sacrifice to appease fans frustrated by another squandered opportunity. McNabb made that easier last night.

But if he pulls the rug on his quarterback, Reid must do it knowing that he let McNabb down more than McNabb ever let him down.