The fallout has now descended after what was a rather eventful day at the Emirates on Sunday and the majority of fingers are being pointed squarely in the direction of Louis van Gaal.
The Dutch manager most likely entered the game in high spirits with his team sitting atop of the table but he and his army of Red Devils were brought crashing back to reality after Arsenal literally tore them to shreds.
Van Gaal's troops left the North London turf wounded after simply being outclassed. A 20 minute offensive onslaught from the Gunners led by talisman Alexis Sanchez was the first time a United side had conceded a trio of goals inside the 20 minute mark - a statistic which Van Gaal did not want on his illustrious CV.
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So, was this lethargic and totally inept performance by United just a one off? Sadly I think there are problems deeply engrained in Van Gaal's squad and ones which will not simply disappear overnight.
When they reached the summit of the Premier League table just over a week ago the feat was met by confusion and disbelief because this was a side that all throughout the season looked beatable in near enough every game. Apart from a 3-0 win against a Sunderland side, who are also a shambles at the moment, the rest of United's matches have provided few positives despite the results.
Anthony Martial and Chris Smalling have been far and away the brightest sparks in United's season thus far, but defensive and midfield issues have been glaringly obvious ever since the first ball was kicked.
Arsenal were the first team this season to exploit these issues to the maximum, their midfield technicians put a pedestrian United midfield to the sword as Bastian Schweinsteiger and Michael Carrick pathetically tried to press the Gunners freeing up endless amount of space for the likes of Mesut Ozil and Aaron Ramsey to operate.
Teams will now realise that if they simply restrict United's time on the ball in order to slow down the pace of the game they can be picked off with relative ease - they do not possess the athleticism to compete in a fast paced tempo.
Wenger's men were also the first team to prove conclusively that Daley Blind is simply not a centre-half. Van Gaal's utility man has been questioned all season but has escaped criticism due to teams rarely testing him. Arsenal did test him, rigorously and the end result was inevitable, proof that his future in a United shirt lies elsewhere.
As for wingers in full back positions, this Van Gaal experiment which he has tried on numerous occasions at the likes of Barcelona failed once again. Luke Shaw's injury was unfortunate but the lack of cover brought in during the summer means United lack strength defensively on the flanks and teams of Arsenal's calibre will target this and benefit from it.
Elsewhere Wayne Rooney offers another tactical dilemma for Van Gaal, his lack of defensive nous and man marking further weakens the midfield and even more worryingly he no longer seems to be a viable goal scoring option.
Problems have been building at United for a while this season and now they have only risen to the surface because Arsenal have revealed them to the world. Van Gaal will search for solutions during the international break, but one thing is for sure, things are not as positive as they may have seemed at Old Trafford.