De Gea has had his ability questioned at various times over the last couple of years following his switch to United from Atletico Madrid, but in February Hernandez declared his confidence in the 22-year-old, claiming that "in a couple of years he will be the number one in the world".
Since then, De Gea has helped the Red Devils to clinch the Barclays Premier League title, been named in the Professional Footballers' Association's team of the year and, with Spain, won the European Under-21s Championship in Israel, where he kept four clean sheets in five games. And Mexico international Hernandez told Inside United: "For me he's the best goalkeeper in the world."
He added: "We all talk about development and having to go down a certain career path and, of course, at his age many people would have been scared to give him the place he's earned for himself.
"But I think that this season (2012-13) he's really benefited from being given the opportunity to play on a regular basis.
"He was first choice between the sticks and I think that any player in the world shows his true ability when he gets the chance to have a decent run of games in the side, and David has really shown his quality.
"He was voted the best keeper in the Premier League, so I'd say he's doing very nicely thank you."