Nadal might struggle to win off clay but he is still usually a lock for the SFs of Wimbledon. 10 years ago you had Guga ranked #1 and losing in the first round of Wimbledon after winning RG. THAT'S different surfaces.
No, THAT's different players. Did Guga win 7 RGs in 8 years? Did he win 16 clay Masters (and counting)? Are you trying to say Nadal is a random clay courter and Fed just a random hard court specialist?