A lot of this is luck of the draw. If a player has the game style that is suited to the court, conditions, string technology, and game style. I do not think that Nadal would have done as well in the 80's because the string technology was different and the speed of the surface and the balls were different. Hence I think Agassi would have done better today. They are all great players it is just lucky as to all of these factors when they are in their prime.
Wilson 6.1 95s