Coming into Texas Stadium, on national television, there would be no way to cover up. If the Eagles were frauds, the whole world would know.
They are not frauds. They are good, possibly very good.
The Eagles passed this acid test by trading big plays and long drives with a Dallas team that every reasonable NFL observer knows is a strong Super Bowl contender.
In a way, the Cowboys' prowess is a good thing for Eagles fans. If the 'Boys weren't awfully good, you would be worried about the Eagles' defense and special teams today. Tony Romo and Terrell Owens and Marion Barber and rookie returner Felix Jones are among the best in the NFL at what they do. They're going to make some plays. The Eagles managed to survive those plays and maintain control of this game until a routine handoff turned into a fatal mistake.
By the same logic, the performance of McNabb and the offense is all the more encouraging because the Cowboys have an elite defense. DeMarcus Ware, Marcus Spears, Bradie James, Roy Williams and Adam Jones - these guys bring it.
McNabb didn't just handle the pressure, he thrived in it. He made a couple of those head-shaking, how'd-he-do-that escapes from almost certain sacks. He shook Greg Ellis off in the second quarter, somehow eluded two other Cowboys, and ran for a first down. That set up a 22-yard field goal.
In the third quarter, McNabb did it again. With Ware closing in on him, he stepped up and underhanded a pass to Brian Westbrook. Instead of a third-and-long situation, the Eagles had another first down on a drive that ended with a touchdown.
Factor in perfect throws to DeSean Jackson for what should have been a touchdown and Jason Avant for a couple of big first downs, and McNabb answered any reasonable questions about his fitness to be a first-rate quarterback in this league.
The unreasonable questions are best left to the unreasonable to discuss among themselves. They invented message boards and talk radio for just that purpose.
The really interesting question isn't whether McNabb is good enough to take the Eagles back to the playoffs - he is - but whether he's better equipped to go further than Romo is.
Cowboys fans will point to the scoreboard, and that's a pretty good argument.
Romo made the blitz-beating throw to Barber to start a fourth-quarter scoring drive, then made the long throw to Jason Witten to set up the winning touchdown.
Romo's pretty good in his own right, no argument there.
But he also threw a terrible interception to Asante Samuel to set up one Eagles touchdown, then fumbled clumsily in his end zone to give the Eagles another. It was almost as if someone told Romo to expect a playoff-type atmosphere, because he delivered one of his slapstick playoff performances in the first half.
When both quarterbacks were given time to operate, both were terrific.
When forced to handle pressure, though, McNabb was significantly better. And since that's a big part of playing quarterback in the NFL, it's a pretty good argument that McNabb is the better all-around QB.
Again, the scoreboard is a fair counterargument. And Romo's throw to Barber with Chris Gocong in his face was an even better one.
What made this game so fascinating was seeing McNabb at full health and with a full complement of offensive weapons. During the three seasons Romo has led the Cowboys, McNabb has seldom had either, let alone both, of those assets.
It turns out Owens is still better than any single Eagles skill player - not to mention any Eagles defensive back. And it turns out that a special-teams touchdown will go a long way toward deciding any close game between otherwise evenly matched teams.
Yes, and it turns out that wretched officiating will leave both teams feeling a little squeamish about how things played out. The crew that worked this game seemed to be trying to make "downgraded" referee Ed Hochuli feel better about himself.
But that wasn't the lesson of this game.
Ultimately, this was a loss that could cost the Eagles dearly late in the season, when they're fighting for a playoff spot. But it was just as clearly a loss that made you think they'll be doing just that.
Contact columnist Phil Sheridan at 215-854-2844 or email@example.com. Read his recent work at http://go.philly.com/philsheridan.