Sent off, correctly, for a rash, late, high — and completely unnecessary — professional foul on Stewart Downing just before the hour, Rooney insisted after the game that the inexplicable moment of madness was not an indication that he is returning to the wild behaviour that plagued his earlier career.
Meanwhile, van Gaal was also fighting a rearguard action over the incident, insisting Rooney need not change and need only commit such fouls in a more “friendly” manner in future. It was significant, however, that the only time the pragmatic Dutchman appeared to lose his cool was when quizzed whether the incident made him question the wisdom of having appointed Rooney captain in the first place.
However, that same pragmatism also ensured that van Gaal is all too conscious that Rooney’s irresponsibility means that he will now sit out a three-match suspension that will put him out until November.
“For me he doesn’t have to change. He just needed to do it in a more friendly manner,” said van Gaal. “He said that to me afterwards. That the challenge was more unfriendly and that was maybe his biggest error because I think he did it at the right time.
“He is for me an example for the squad. That I saw in the USA and when he came back he kept that example and that’s why I made him captain, because he is also a great player.
“And as you know, when you are my captain, you have more privileges, and you have to play always more or less, and I have to be sure of that, so that is also an argument. And I saw in advance that he would play a lot of times.”
To his credit, Rooney faced the media after the game to explain the sixth dismissal of his career, the third for United, and one which took the gloss of the 10th anniversary of his United debut, which he marked yesterday.
The England forward, whose actions unfolded before the watching Roy Hodgson at Old Trafford, conceded that he had apologised to his team mates after the game but that the red card in no way shows a streak of ill discipline is returning to his game.
“I expect people to say that, but at the end of the day, I was trying to break up the play,” said Rooney. “It was a dangerous situation in that they were trying to break on us and I have just misjudged it, simple as that, but I have no complaints.
“Obviously we got away with it by getting the win, but I am gutted that I am going to be missing the next three games.
“I just have to make sure I train well and be ready for when I come back.”
Despite the sincerity of the words, however, Rooney has simply ensured that a player whose every action unfolds under an intense spotlight will be viewed even more keenly upon his return from suspension in November, although his manager has no concerns about his captain’s future conduct.
“No, no, no. Because he came at once to me and said it was not his meaning to do it like that,” said van Gaal.
Rooney had demonstrated the other side of his football personality after five minutes, a committed, well-timed run taking him into the area where he converted Rafael’s cross superbly.
Robin van Persie’s second goal, after 22 minutes, would have wrapped up the points for United in days gone by but, given defensive frailties, it was no surprise that Diafra Sakho pulled back a goal before the interval.
In a frantic finale Kevin Nolan had an ‘equaliser’ ruled out for a narrow offside decision and United’s Northern Ireland debutant Paddy McNair capped a solid display with a magnificent clearance that saved an equaliser.
Indeed, one of the few consolations for van Gaal during his current defensive injury crisis has been the emergence of youngster Tyler Blackett and, now, McNair.
“I saw the clearance he made at the end and I thought he was tremendous for us,” said Rooney of McNair.
“This is probably one of the bigger tests a young defender can face, up against a team putting in lots of crosses into the box, but he took it and stood up to it, especially in the second half.
“It won’t get much tougher in terms of physical strength and aggression against him, but he dealt with it and we are all delighted with him.”
MANCHESTER UNITED (4-1-3-2): De Gea 5; Rafael 7, McNair 7, Rojo 7, Shaw 6; Blind 6; Herrara 8 (A Valencia 74), Rooney 5, Di Maria 7 (Thorpe 90); van Persie 7, Falcao 6 (Fletcher 65, 7).
WEST HAM (4-1-3-2): Adrian 5; Demel 6 (Jenkinson 65, 7), Tomkins 7, Reid 5, Cresswell 6; Poyet 6 (Nolan 75); Song 6, Downing 7, Amalfitano 5 (Cole 61, 6); Sakho 8, E Valencia 6.
Referee: L Mason 6.