historically, isn't goalkeeper the one position where the US has been able to develop a number of high quality players? I guess that's because it is a different set of skills, but it seems the US more or less gets as far in international competitions as its goalkeeper takes them. It sort of makes sense that MLS might be a place to find one relatively cheap.
From an outsiders perspective, absolutely.
Keller, Friedel and Howard, off the top of my head, were top quality over here. I never rated Guzan though.