When Blackburn beat United at Old Trafford on New Year's Eve it appeared to signal a temporary halt to De Gea's campaign. He was left out for four games, including key wins at Manchester City and Arsenal, and if deputy Anders Lindegaard had not picked up an ankle injury in training, the Spain Under-21 star might have remained on the sidelines for the rest of the season.
Instead, De Gea returned against Chelsea, produced a magnificent save to repel an injury-time free-kick by Juan Mata, and has not looked back, with Ferguson saying: "It's similar to what we were saying about Steve Kean. He got a grip of it and stood up as a man."
He added: "The area where he's been criticised was the aerial ability in the box.
"He should have dealt with the last corner against Blackburn (on New Year's Eve) better. He knew that.
"He has addressed that section. He didn't let it get to him and now the boy is playing with confidence. And confidence is a great factor in football."
That does not mean De Gea is suddenly dominating his penalty area in the way legendary United keepers Peter Schmeichel and Edwin van der Sar used to. However, he is starting to understand the need to impose his presence in penalty box situations and, at just 21, he has plenty of time to learn.
"It took him time to adapt to the different ways of the English game and he is showing that now," said Ferguson.
"The other night [against Fulham] he made two or three really terrific punches and blocks in the first and second half when they started to propel the ball into the box.
"He has shown fantastic improvement. We expected his ability to show and we are seeing that now."