For know I still doubt that David De Gea is the best goalkeeper. I think 2 years again David De Gea can make a best goalkeeper in the world. David De Gea untested in the national or European level team. If in the World cup can get champions I will agree he is the best goalkeeper in the world.
Winning the world cup doesnt really mean that you are a great player, in fact messi has never win anything and yet he is one of he best player in the world. Real madrid was desperate enough to sign de gea last time and that proves that he is the best as they only wants to sign the best goalkeeper at those times
Manchester United had been any problem to the goalkeeper positions several years ago because Roy Carroll as the goalkeeper doesn't ever playing good on every match even Ferguson complained that but i think since De Gea coming to Manchester United he has playing more better rather than Roy Carroll so in my opinion De gea still the best goalkepper for Man Utd currently