Good point, it seems to be thing that because our num 2 keepers over the years have been dismissed by some fans that they are no good. I have heard fans over the years slagging the likes of Freidel, Vorm, Cudicini when in all honesty they have all been good keepers.
It seems some fans can not get past the fact that because they are not first choice they can not be any good.
It depends on several factors, though. I don't think anyone can claim that any player earning money playing in the top division, in the arguably hardest league in the world is no good. Even if they're second choice. Question is what you aim for, and how the rest of the team is assembled. Rather, if they're good
enough. There's a difference between being good enough to stay in a division, and being good enough to win it. Players like Dejan Lovren is not an elite defender by any stretch, but the rest of the team can make him look better (or stand out as less good). If he was their mainstay in defence, they would not have won the Champions League, that much I'm pretty sure of.
A keeper like De Gea has his faults, but they are few. Then again he has the ability to do the exceptional, and both can and have singlehandely saved United from embarrasment - irritatingly enough also against us. Lloris is the same, arguably a tiny bit less so. Keepers like Gazzaniga, Vorm et al rarely lets in goals they're expected to save, but then again they rarely do anything you don't expect them to, either. Heurelio Gomez did pull off exceptional saves, but let in unbeliveable goals as well. He was a De Gea with more faults. Gazzaniga, as I've seen him, is solid. He's good. Of course he's good. Nothing more. Exactly what I would expect from a backup keeper. Keepers on his level will not feature as first choice on a title winning team in a competitive top level league, because sometimes you need keepers to do the exceptional to do so. Otherwise, they're rarely a title winning team.