It gets pretty simple from here.

Donovan McNabb must start next Sunday's loss in Irving, Texas, for two reasons: first, because the Eagles are still mathematically (if laughably) alive for a playoff berth and, second, because it would be cruel to make Kevin Kolb start his first NFL game against that team, in that environment.

If McNabb can somehow lead the Eagles to a win against the Dallas Cowboys, then he starts in New Orleans on Dec. 23.

If not, then Kolb starts the last two games of the regular season, at New Orleans and home against Buffalo.

When the play-the-kid talk started earlier this season, the feeling here was that McNabb had to keep playing. He deserved the chance to play through the recovery of his surgically repaired knee. Just as important, the Eagles needed to see where McNabb was at least as much as it needed to see Kolb, this year's top draft pick.

After yesterday's 16-13 loss to the New York Giants, that has changed. The Eagles know where McNabb is. They must either decide to believe he will be better after another off-season or that this is as good as he's going to get, then make a final evaluation on their badly muddled quarterback situation.

That means learning something about Kolb. Now that A.J. Feeley has played his way out of consideration as a stopgap, it comes down to No. 5 or No. 4: McNabb based on what he has been or Kolb based on what he might be.

This wasted season is the result of a series of miscalculations. McNabb came back too soon to be at full go. That doesn't mean he will regain all the physical gifts that helped make him a special QB, but there is no doubt the injury hampered his mobility, which affected his decision-making, which in turn eroded his confidence.

McNabb's limitations were magnified by the lack of talent around him on the offense. Brian Westbrook is an exceptional player and will be excluded from another Pro Bowl only if there is a complete breakdown in the selection process. But the receivers, including injury-plagued tight end L.J. Smith, are ordinary at best.

Let's not even get into the play calling debate here. Even the most fervent anti-McNabb partisan will have to admit that Andy Reid and Marty Mornhinweg game planned and called plays as if McNabb were as healthy and effective as he was in 2004. So let's leave it at that: The coaches didn't factor in McNabb's physical limitations or the caliber of his wide receiving corps (which, of course, the coaches gave him in the first place).

Asked to carry the offense with one good leg and one good weapon, McNabb fell short. The only thing surprising about that is that anyone finds it surprising.

Look at the Eagles' two losses to the Giants.

On Sept. 30, with Westbrook, Smith and left tackle William Thomas unable to play, the Eagles' pass-crazed approach got McNabb sacked an NFL record-tying 12 times. The mismatch of Osi Umenyiora and inexperienced tackle Winston Justice led to six sacks and had Michael Strahan wondering aloud what the Eagles coaching staff was thinking. He wasn't alone.

Yesterday, McNabb returned after missing two games with ankle and thumb injuries. He looked as mobile as he did before spraining the ankle - not as quick as he once was, but able to move around, buy time and take off for the occasional run.

He completed 20 of 30 passes for 179 yards. But his longest completion was just 19 yards, and that was on the final desperation drive. The Eagles couldn't or wouldn't throw the ball downfield, even though the Giants were playing two backup safeties.

"The ones we called," Reid said, "we had a little bit of pressure [on McNabb]. We called a number of them, but we just weren't able to get them off."

That sounds like a knock on the QB: a "little bit" of pressure, not "able" to get the passes off. Reid doesn't offer much, so it's fair to interpret the way he chooses not to say much.

The killer sequence came in the third quarter, when a rare turnover gave the Eagles the ball on the Giants' 8-yard line. A false start by guard Todd Herremans and a sack taken by McNabb pushed the Eagles back to the 19. A touchdown instead of a field goal there changes the tone of the game.

The combination of McNabb, the surrounding cast and the play calling couldn't get into the end zone. That has been the story all season. It makes sense to try different combinations before long-term decisions have to be made in the off-season - but not until after the Dallas game.

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