It was a shame that Louis van Gaal had the 9pm Virgin Pendolino north out of Euston to catch because he had so much more to say. He was richly satisfied - as satisfied as we have seen him. And who could blame him, after Arsenal had conspired to make his tactics look like a work of genius when they had been given every chance to make a mockery of them.
Van Gaal said that he had reverted to a three-man defence - yet another shift in formation - to make room for two strikers and damage an Arsenal backline that he knew was vulnerable.
It was a risk. Yes, it was a risk," he said. "But I was sure that Arsenal wants to attack and to press us. Then, you know that Arsenal is giving a lot of space away and (Per) Mertesacker and our friend, erm, (Nacho) Monreal has to defend. That's why I put (Angel) di Maria against Mertesacker and (Robin) van Persie against Monreal." But he could not have remotely pictured Arsène Wenger, with all that longevity, sending out a side whose last line of defence would be stranded halfway into United's half of the field when the breakout for the second goal occurred.
That defending, of which Wayne Rooney was the ultimate beneficiary, belonged to junior-park football and invited the delicate inquiry as to whether Wenger actually prepares his players tactically for balancing attack and defence when they find themselves 1-0 down.
His reply was extraordinary in its air of resignation. "We were 1-0 down and we wanted desperately to come back and forgot a little bit our principles," Wenger admitted. "I have to see it again because I was surprised there was nobody there any more.
"They want to do well. I have a lot of respect for this group. They have a great attitude, great spirit and great energy level. But maybe the disappointment of being 1-0 down, everybody wanted too much to go forward…"
He reiterated the statistics he had been reciting for the previous 48 hours: that Arsenal are one of the three quickest teams at winning back the ball and allow least penetration into their final third. He was whistling in the wind. This is Arsenal's worst start to a season for 32 years.
Their perennial vulnerability to a counter-attack owes as much to the lack of a physical central midfield force as to the weakness of a defence which was spared humiliation by Di Maria fluffing another counter-attacking one-on-one chance at the end. But Arsenal's wild abandon would not have been necessary had Danny Welbeck not demonstrated so emphatically why Van Gaal was right to let him go. It is hard to overstate how catastrophically unstable United's three-man defence looked in the game's first half hour when, quite frankly, Luke Shaw seemed traumatised by the process of deciding whether to stay back or go. His removal with an ankle injury was a salvation. Welbeck simply lacked the ruthlessness to capitalise.
"Ruthless (is what you need to be) for sure because when you are in the box and you can't manage to score in that many situations you can't expect to win a football game," admitted the Arsenal captain Mikel Arteta.
It was the weakest, most vulnerable United side ever to have pitched up at the Emirates and still Arsenal found themselves rolled over.
United's Chris Smalling, who recovered from a frantic opening to impose himself on the three-man defence admitted the display had not been good: "Given the manager and the players we have got, we should be playing better than we are, with more points. We did not play well."
But Van Gaal's United, now up to fourth in the Premier League table, are demonstrating the ability to take points while being second best.