It was not really the Spaniard's errors that were the problem for me; I thought his mistakes for both goals were relatively minor and he was undone by some poor defending.
What really bothered me was his apparently complete lack of confidence.
It makes me wonder if he will be able to handle the scrutiny he is under at the moment.
Has he got people here to support him? Not just at the club, but also family and friends.
When most goalkeepers make mistakes they get angry - or, in the case of the ex-England keeper Ian Walker, they smile - but nearly all offer some sort of reaction.
However, De Gea doesn't do anything at all. He is expressionless, and looks lost.
If he were a poker player, he'd probably be very successful, but for a goalkeeper it is not a good sign.
It chimes with the way he plays the game. Every goalkeeper makes mistakes, but De Gea seems worryingly passive.
Peter Schmeichel made the odd howler, which usually stemmed from making a rash decision - but at least he did something.
De Gea's mistakes come from not doing anything. He freezes, and appears indecisive.
He is a talented goalkeeper and, at 21, has time to improve.
But at the moment he looks something of a liability, and although Anders Lindegaard is a more confident replacement he is hardly a top-class goalkeeper.
I would like to see him go back to Spain on loan, to regain his confidence and gain a bit more experience.
United just need a solid, Premier League goalkeeper in the meantime, and there are a few of those.
Mark Schwarzer isn't getting any younger, but if he can do a similar job to the one Brad Friedel has done at Tottenham he will be fine for a season or two.
De Gea has played big matches in Spain, but I think it's a different game over here.
There is much more contact, many more balls flying into the box and more pressure on the keeper.
I think even Iker Casillas would struggle in the Premier League, I really do.
The problem with De Gea is that his confidence is rock-bottom, and it is spreading to his team-mates.
United should not cut ties with the Spaniard, but a spell away from the harsh spotlight of playing in goal for Manchester United would surely help.