For a manager of LVG's experience and acumen to be outwitted and out-thought by a man 30 years his junior who has been in management for just over a year was extraordinary.
With his Swans side 1-0 down, Garry Monk reacted by taking off Wayne Routledge in place of Ki Sung-Yeung, switched to a midfield diamond and pushed the impressive Andre Ayew further forward.
The change of personnel prompted a change of fortunes for Swansea who turned the game around to triumph with two goals in five minutes.
Granted, it's the job of the manager to make decisions such as this to turn a match around, but when Swansea altered their shape United did not and they made us pay.
Sometimes football yields an image to neatly express disorder and confusion.
Here, it was the sight of Marouane Fellaini pressed into service as an emergency striker for the last 14 minutes with United chasing the game.
Van Gaal basically admitted that a team packed with experienced internationals was not able to cope with the change quickly enough.
He did not react- and Swansea scored twice in those minutes.
That substitution confirmed the paucity of United's lack of attacking options as Rooney slipped into a withdrawn role to escape the pressure of being the Reds only A-list front man.
Contrast that with Monk's vibrant, brilliantly potent attacking team and it is not hard to see why, yet again, Swansea got the better of LVG's side.
Not only did LVG fail to react to a change in the game situation but, when he did, his choice of replacements were odd.
Michael Carrick sent on to try and salvage a result?
Fellaini as a centre forward?
Javier Hernandez (perfect in circumstances such as these) as an unused substitute having been told he can leave?
I also can't help but feel that, had David De Gea been between the sticks yesterday, he most likely would have saved both of the efforts that led to Swansea's goals.
Juan Mata is a number ten, not a winger, Daley Blind is a midfielder/left back not a centre half and Wayne Rooney is better behind the frontman not the lone striker.
United have the right components but are not clicking as a unit.
These players are not being utilised properly and, until they are, it's hard to see the progress United fans want- or rather- demand.