GK is a strange position. They can go from being regarded as one of the best in the world to being relegated from the PL and being pretty average in a few years - Cesar
Tom Howard was excellent when he joined United, Dudek was excellent when he joined Liverool, we know how both of those went.
David James hailed as the next best thing, Robinson, ditto
Young keepers are what they are, iker casillas is one of the exceptions, he took the real No.1 and kept it. A really great keeper but even he made mistakes as all young keepers do.
De Gea will do as others have done, get more experienced and improve his overall game. Hart will too. Cech is getting back to pre fractured skull form. There are some excellent keepers in this league that's for sure. reina has had a bad spell but seems to be returning to form of late.
But all keepers made the odd flap, even the likes of peter and edwin, Edwin v Fulham, that was a comical ****up for such an experienced keeper

I am sure he was embarrassed by that one but they all have those moments and always will, the great keepers don't let it affect the rest of their performance and the following games.