Dude, if you're not going to read what I am writing then there is no real point in discussing it.
Sampras played in an era when one surface was highly suited to his game (grass) two less so, and a fourth completely hostile to it (clay). Nowadays all surfaces pretty much suit all players. There are some differences but they are pretty minimal by comparison.
Clay in 2013 is not different from clay in 1993. Let me spell it out to you:
Nowadays all (top) players are well adapted to pretty much all surfaces, not the other way around.