Any close study of Nibali and you would know better.
It's always the same pattern.
Dauphine 09, Tour 09, Giro 2010...
hang with it...hang with it...hang with it... until you blow.
Especially on the longer, and long/steep mountains there is a point where he just simply cracks, at least twice during a grand tour.
As long as pure climbers participate, it's always the same. The only thing he improves in is hanging on longer and longer.
In his first years he was good enough to finish just top 20 in GT. Then it became top 10, and now top 5.
But there's always the 1 climb he blows, loses 2 minutes, and can forget about GC...
Unless he finds a GT field without Anton, Mosquera, Contador, Basso, Gesink, Scarponi, Andy Schleck, Denis Menchov, Jurgen Vandenbroeck and *name topclimber here*
Then perhaps..