While I think Saberq is a complete fool, I don't think you're right about this either. The physical aspect aspect of today's game, in virtually any sport, has made pretty much every single sport so very different. This is especially the case in tennis. To say that the players today are inferior athletes to the champions of the pre-Open Era is just as absurd as Saberq claiming that Laver would get destroyed by Federer. Yes, many of them were very fit, Pancho especially, but today's players are not only fit, but they are strong as well.
I don't think most people will deny the game is more physical today than it was 40 years ago. Pound for pound, the top 100 is faster, stronger, fitter, than it was even as recent as 15 years ago; both Sampras and Agassi themselves remarked this to the media and in their books alike. The point is -- for the purposes of this thread -- why is this even relevant? Laver, Pancho, and the like, didn't have the benefit of 2000's nutrition, technology, and sports psychology, yet they still dominated their era much like Federer. Give them
these benefits and all the sudden people think they're gonna do worse?
Personally I think the only major difference is that those top guys wouldn't dominate quite as long
as if they were playing today -- since the mileage racks up on the body a lot quicker under today's conditions. The lack of sports globalization has to be taken into account as well, as well as the risk, time, and expense of travel (particularly pre WWII) but this takes nothing away from these guys games; or their mental toughness. These guys were fucking champions, the greatest athletes of the world at their time -- all you can do is dominate the era against the tools and technology you're given.