Re: Will Nadal be better than Ferrer at the age of 31?
Rafa has about 3 to 5 more RG left on him if his knees hold long enough, otherwise it'll be about 2 or 3 more, Wimbledon is always a possibility, but I realistically see Roger winning more and more because his talent is so easy on his body, AO is always open and Rafa can win some of those, but USO? he'll be lucky if he wins one, because his knees are never well by that time of the year.
If Rafa can remain healthy, his potential talent will always make him more successful than Ferru. But that "potential" has to have a foundation. This question is impossible to predict only because of Rafa's disconcerting and unpredictable health concerns.
Roger was faster in his prime and hit his FH better but now his BH is far more consistent; and his serve while it isn't the fastest one in the circuit is incredibly effective due to the fact that he can hit it with any effect and to any corner he wants, it's very difficult to read if he's in a good day. So he has adapted well to growing older. That is another question one has to consider. Does Rafa have the capability or even the desire to adapt as he grows older the way Roger has successfully evolved?