I would concur with what several of you have already said. I really don't see how Rafa could continue by just playing the grass and clay seasons. Would he be allowed to do that? I just don't see it. If he was allowed to do it surely it would cause chaos. Wouldn't you get a lot of the players turning around and saying that in future they will only play on the surfaces that suit them best? Mind you, it would be one way to shorten the season
Seriously though, if I was Rafa, and I really thought I would have to restrict myself to a specific part of the year, I would wonder what the point is. I know the urge to compete is strong, and it's hard to push that away, especially in a player who is relatively young still, but I think you have to be a bit realistic as well. I just think if it was to come to the point where Rafa couldn't play for a considerable chunk of the year, he would probably be silly to continue. Wouldn't it be better to stop and leave people with good memories, rather than continue and just have people focusing on these times when it has clearly become a struggle, at least physically?
At the risk of sounding unkind, and not really meaning to, I do wonder if part of Rafa's issue with the hard courts is partly that the surface doesn't entirely suit him. Now admittedly I haven't looked at his whole record, but certainly in the slams it is clear where Nadal's strength lies. He's won 1 AO, 1 USO, and the rest of his major titles have all come on the clay and grass, especially, obviously, the clay. The trouble, at least from his point of view, is that he can't expect the ATP to drop a surface just because he doesn't like it. He should know damned well they'd only do that for Fed
As for Andy, I took the comment about him taking painkillers before playing on the hard courts to mean that this is what he has done this year, at the USO. I didn't see it as being something that he would do long term. I think you have to put it in context. Firstly, this part of the year has been very busy, more so than usual, because of having the Olympics on top of a schedule that is already quite cramped. Muscles, joints, etc, are bound to be sore at this point. I think it also depends on what is meant by painkillers. If it means something very strong I would be worried, but it could mean just a couple of paracetamol or something like that before a match, just to ease the aches and pains somewhat, in which case I don't see a problem.
In Djokovic's case I really wish he wouldn't slide like he does on the hard courts. One of these days he's going to get that horribly wrong and it won't be pretty. He's definitely got elastic ligaments though, I'll give him that. That said, in the final I was surprised by how Andy managed to get Djokovic down a number of times. I don't recall ever seeing Djokovic spending so much time on his backside before, or losing his balance. It was amazing stuff.