The Spanish youth international has come in for criticism for a punch that he made in the build-up to Tottenham Hotspur's goal at the weekend, particularly from former United defender and now-pundit Gary Neville.
However, Banks has admitted that he was "very upset" to hear Neville's words.
"I was very upset to hear Gary Neville talking about how the players were disgusted with [De Gea], how they were looking at him, after he hadn't punched the ball quite clear enough," Banks told Press Association Sport. "I thought to myself, 'hang on a minute, it's not just the goalkeeper that makes mistakes, everybody makes mistakes in football matches'. I couldn't quite believe that, because if anything he would've liked a bit of a lift. 'Come on, get your head up.'
"I found that a bit strange that [Neville] was saying they'd go back in the dressing room and give him a telling off.
"De Gea's got very good reflexes, makes excellent saves you think other goalkeepers probably wouldn't have got. He's got lots of years left yet. What he needs to do is to practice on the crosses as much as he possibly can."
You can read Neville's verdict of De Gea here.