Re: Roger Federer
Agassi's prime is kind of hard to define. Between at least two of his GS victories, he had fallen to below 200 in the world.
It was Agassi's up and down that made many say the same thing about Sampras(didn't beat anyone.)
The real problem that started to manifest itself in the 90's and seems to have continued today is the degree of specialization.
In the 90's you had guys like Berasategui and Muster on clay, and Ivanesivic on grass who wouldn't win anywhere else.
Now finally with Federer and Nadal you have two guys who are a threat on any surface but yeah its' really just those two. Djokavic can't be trusted to not be throwing a match and Murray has been hyped but hasn't produced much in Grand slams.