Arsenal's tentative and clueless possession play and hesitant defending gifted the Red Devils a comfortable victory. It was a stroll for United, rather than a grind, and the fault lies with Arsenal's lack of bravery and assurance when on the ball.
United had plenty of chances and certainly put the Gunners back four under pressure. However, that was to be expected from the English Premier League's in-form team in front of goal. Although Thomas Vermaelen once again showing that he is more enthusiasm than skill as a defender, will surely concern Arsene Wenger.
Yet the real problem was what Arsenal did, or didn't do, when they had the ball. It was disappointing to see a Wenger team almost scared to go forwards.
Everyone was guilty, including the much lauded midfield trio of Mikel Arteta, Santi Cazorla and Jack Wilshere. Arteta battled hard, but couldn't effectively influence the attack. For Wilshere, the game simply seemed too big at this stage of his recovery. He ultimately paid the price for trying to compensate with aggression, when he couldn't cope with the pace of the game.
Cazorla was arguably the biggest let down, despite a superb last-second strike that put some gloss on an otherwise uninspired showing. The main problem was that Cazorla was often far too deep to exert his usual creative influence.
Part of this was due to United's pressing, but, as the key man in Arsenal's formation, Cazorla has to position himself in the areas where he can do the most damage. It is his responsibility to find and create space for himself in the attacking third.
Cazorla's poor range of movement was a malady that plagued the whole team. There never seemed to be sufficient options for the man in possession.
That's because there was no real urgency in the midfield and forward areas. The result was that many players' first thoughts were to pass the ball backwards.
Yes, United play with a disciplined shape, but fluid movement can create openings against even the most stable tactical structures. Wenger has to encourage more verve and urgency from strikers Lukas Podolski and Olivier Giroud.
Arsenal may have been jaded given their recent shaky performances in the EPL and UEFA Champions League. They may also have been mindful of the 8-2 thrashing United inflicted on them at Old Trafford last season. However losing by five fewer goals than they did last year, simply doesn't qualify as progress.
If Arsenal hope to salvage their top four hopes, they must rediscover their swagger in attacking areas. Wenger's men must be bold enough to take chances and try different ideas to create scoring opportunities.
If not, then the Gunners will continue to pose little to no threat to the top teams and find contests against the rest a serious struggle.