He's also 35 and had injuries lately. If you want to beat Federer you are going to have to be one of the best tennis players the game has seen. That's the point--these guys are still great players and props to then for preserving their careers. The young guys can preserve their careers when they get older, too.

The young guys are not all time greats because they just aren't good enough yet. You're argument is extremely weak IMO.... Great players thrive on competition and a desire to be the best---the fact that the two best ever are still in the game should give the young guys all sorts of motivation and focus. 20 year olds like Zverev have no problem playing a full schedule... He's 20! When I was that young I used to play 2 matches a day and never felt like I needed rest.