I do agree scheduling wisely will be key for JMDP to do anything meaningful in the coming years, in his case it's absolutely imperative. He has been guilty of passing cheques his body can't cash far too often; I understand he was eager to return to the top 8 for seeding purposes but now that he's there he should really schedule wisely and attempt to peak for the big events imo.
Well, I think that answers the question discernibly. If Del Potro wants to try and gain momentum and consistency, he needs to stay injury-free. One of the integral ways in doing such a thing is schedule wiser and not constantly travel/compete. It's really that easy. If Delpo wants to start achieving satisfactorily bigger results at significant tournaments, he needs to slap himself on the wrist (preferably right; don't want to harm the left), and get his shit together. If he continues at this erratic rate, this type of inconsistency and substandard results will follow him into the end of his career. If he's happy with winning the odd 250 and 500 title here and there, that's fine by me, but a whole load of talent is being washed down the drain. At the moment, however, Ferrer is still clearly #5. Like I said, I'd feel safer betting on Ferrer than Del Potro against another top 30 player.
And can I see someone troubling the big four, mentally, at an important event? Sure. Berdych against Federer.