The Dallas Cowboys defense, made up of a number of journeymen, unheralded draft picks and previously underperforming reclamation projects, has managed to produce at a level few expected thus far this season - they're almost the perfect physical embodiment of the notion of a whole being greater than the sum of the parts.

But is that unexpectedly capable defense on the verge of collapse - especially as it prepares to face a Philadelphia Eagles offense, on Thanksgiving Day in a battle for NFC East supremacy, that's built on principles of speed and tempo?

The Cowboys have been hovering around the middle of the pack all season in terms of total defense - they're currently 14th in points (21.8), 16th in yards (355.0), 19th in passing yards (247.8) and 13th in rushing yards (107.2), according to NFL.com.

This is - mostly - by design.

With a profoundly talented offense that is expected to score each time it touches the ball, defensive coordinator Rod Marinelli's bend-but-don't-break philosophy is the purportedly perfect complement, says Rick Gosselin of The Dallas Morning News.

The Tampa Two defensive scheme of Marinelli is designed to prevent big plays. Keep the ball in front of you and make the opposition work for its scores, figuring if the offense must snap the ball nine or 10 times on a possession, it will eventually make a mistake.

That's the theory at least. The problem is, with a defense devoid of any major stars and perilously thin at a number of positions, there exists a dangerous lack of players that possess the ability to step up on that tenth snap and make a play or force a game-changing turnover.

But that hasn't been happening with this defense. The Giants mounted scoring drives of 14, 13 and 11 plays in those three possessions of 80 yards or more. The Dallas defense seemed more of a sparring partner on this night than a legitimate title contender.

The D in Big D has spent more than 30 minutes on the field five times already this season, according to Gosselin. Three of those games required come-from-behind victories, and two eventually became losses.

The Cowboys, though they managed a hard-fought victory over the, now 3-8, New York Giants on Sunday night, nearly saw the game slip away from them on several occasions. Had Giants quarterback Eli Manning been able to complete a second-down pass to a wide-open Preston Parker on Dallas' doorstep late in the third quarter - New York already leading 21-17 and looking to put the game away - the Cowboys could have been heading into Thursday's game against Philadelphia at 7-4 instead of 8-3. 

Instead, Manning missed high, safety Barry Church intercepted the pass and the Cowboys were able to scramble back to victory, thanks to a late touchdown drive by the offense.

These type of late-game heroics are squarely within the capabilities of Romo and his offensive brethren, but to continue to ask them to lead the team to victory in the game's waning moments is playing with fire that will eventually burn not only the Cowboys' seemingly depleted defense, but fans across Dallas as well.