They really wouldn't have. Their back 4 is bad enough as it is but they get no protection. Our equaliser at Anfield the other week summed Arsenal up; 4-3 up in the 93rd minute and Arsenal have 4 players trying to mark 6 Liverpool players in their 18 yard box.
edit: BTW i mean they wouldn't have sat back rather than Utd wouldn't have scored.
You've got half right half wrong, the back four themselves, Toure, Gallas, Clichy and Sagna, last year had the least losses in the league they are fine. AS you said its our midfield, almost all our goals we've conceded, basically all the goals against you, utd, chelsea, all of them were utterly missing midfield. That 4th goal against you made me cry, it wasn't that Song, Diaby was it Denilson also were up the field and unable to get back, they simply did what they always do, jog back, ignore midfield runners and stop, all of them could have gotten to the ball ahead of your players, in the move they all started off deeper than the liverpool players but every single time they slow down and stop.
There is no back 4 in the world that can mark 6 men in the box well, its quite literally impossible.
The most embarassing thing about it is, it was so obviously clear in our very first preseason game, all through the first transfer window, up to the second transfer window. Wenger decided that we had a problem scoring goals, and the 250% higher goals conceded than Utd compared to the 2 goals less scored apparently didn't matter. SO he spunked all our money on Arshavin, while a simply superb player, he completely ignored our problem. It was only after being trashed by Chelsea, without anywhere near our first team back four with Clichy and Gallas missing and Sagna still struggling after injuries, that Wenger decided defence was our problem this year and has since used them as a scapegoat for the failure of the entire year.
Arsenal would never have won this weekend against Utd, they came out with a weakened team and barely even tried, there was no surging runs constantly throughout the game, no breaking properly, no one really cared, they knew they'd get the point and they didn't seem to be remotely worried. If Arsenal were a real threat, frankly, Utd would have put in proper effort, a better team and actually tried, the fact they didn't try, its depressing, they just sensed no threat at all from us.
I half think that Wengers abnormal love affair with complementing Fergie in the past couple weeks is a desparate cry asking Fergie not to embarasse them, which frankly they could easily have done. We looked half decent against a side that simply couldn't be bothered. When they could be bothered they trashed us in the champs league.