Did the defense really play that bad?
If you're going strictly by the scoreboard, then yes. The more thoughtful answer is probably not. Check out the Saints drive-by-drive.
0-0 starting @ NO 26, 15:00 1st qtr - 8 plays, touchdown
7-0 starting @ NO 20, 9:03 1st qtr - 3 and out
7-7 starting @ NO 47, 5:15 1st qtr - 9 plays, field goal
10-7 starting @ NO 20, 0:57 1st qtr - interception
10-10 starting @ NO 30, 2:38 2nd qtr - 3 and out
10-10 starting @ NO 46, 1:20 2nd qtr - 2 plays, touchdown
17-13 starting @ PHI 22, 14:49 3rd qtr - 3 plays, touchdown
24-13 starting @ PHI 24, 12:58 3rd qtr - 4 plays, touchdown
31-13 starting @ NO 23, 10:26 3rd qtr - 11 plays, field goal
34-13 starting @ NO 27, 0:29 3rd qtr - 3 and out
34-13 starting @ NO 48, 12:50 3rd qtr - 6 plays, touchdown
41-20 starting @ NO 5, 5:12 4th qtr - 3 and out
New Orleans only had one touchdown drive over 54 yards. Two longer Saints drives stalled with goal to go. Four times, the offense went three and out, each time starting no closer than their own 30-yard line. Their average starting field position for the day was at their own 37.
Turnovers, special teams miscues, and penalties were far more responsible for the high score than the Eagles defense. Of course it would have been nice if they came up with at least one big stop when the Saints had a short field, but the Saints have an elite offense that is going to capitalize more often than not when starting at midfield, or better yet, in their opponent's zone. The Eagles lost the field position battle, one of the underrated yet fundamental aspects of the game, and their defense looked silly as a result.
What about the pass rush though?
Understand Drew Brees was sacked a total of 13 times all season in '08. The Eagles got to him twice on Sunday. Not coincidentally, the Saints were forced to punt both times.
After Trent Cole blindsided the quarterback on their second possession, he was chipped and doubled the remainder of the game. That effort combined with Brees's quick release and pocket presence makes him a tough customer back there. He's just not someone who is going to spend the day rolling around in the grass.
That said, this is where not having a productive pass rushing interior lineman really hurts the Eagles. Brees is generously listed at six feet, and any kind of decent pressure in his face makes it more difficult for him to see down the field. They didn't have that on Sunday, and it's fair to say maybe that was an issue. They arguably should have blitzed up the middle (or in general) more frequently, but that's when Brees really starts to carve up a defense.
The bigger question here is how Joselio Hanson (5'9") wound up in one-on-one coverage against Marques Colston (6'3")?
What if they played it again?
The Eagles, particularly with a healthy Donovan McNabb, still look like a decent team. The Saints appear destined for a return to the playoffs. It's not far-fetched to envision a scenario where these two squads meet in January.
Don't get too caught up in the final score. When they went into the locker room, the spread was only 17-13. It was 10-10 at the two minute warning. This was a tight game until two turnovers in Eagles territory basically handed the Saints 14 points, otherwise it had the feel of a game that was going down to the wire.
In other words, the Saints were beatable. Right now, the Eagles have to work on eliminating the number of stupid penalties they take (still with the illegal formations?), particularly on special teams where they racked up five out of their seven total flags for the day. Clean it up, protect the ball, and the outcome might be different next time.