I tend to see a lot of riders looking to 'save their season' at the Vuelta, which usually doesn't end to well (exception of Wiggins last year), with either injured riders or riders who were poor in the Tour looking to right a wrong. Obviously there's still a lot of talent there, but should he produce a solid ride, I can see him finishing top 5. Just stick at it, performing constantly like at this Giro. The course should suit Purito more than the Giro, and with Contador riding I can't see him seriously threatening the podium without an improvement. But a top 5 is possible.
I'm a big fan of hid and would love to see him do well, but without the incredible ride up the Stelvio, which was incredible, he wouldn't of podiumed. The riders behind were ignorant of De Gendt and didn't react when they should've in the valley. If they had at least kept a steady pace, I think he may still have won the stage, but he wouldn't been able to make such a huge leap up the GC.