Dr. Juice said:
He let himself go too much after the Giro. And IMO he had not enough races to build up his form. He had to rush into form after he was shockingly slow in Tour of Poland. Not ideal.
But he underestimated Horner when he let him go in the first mountain stage. That day he probably would have arrived with Horner and not lost 46 seconds. He thought Horner would not go far, playing games with Rodriguez, Valverde and Basso.
Had Nibali been in front with 3 sec instead of 3 sec behind before Angliru he might have won - he was on par with Horner that day or at least not clearly inferior (imo) and had to attack him. Burned himself with those 5-6 attacks. The seconds he lost on that easy climb ( 5,5 % average, not more than 7-8 km long, don't remember the name) a couple of days before were crucial.
I always thought he should hang on to Horner on the Angliru and attack with 800 m to go because Horner is a diesel, not explosive. Take 4-5 seconds and win.
He had a great form coming out of the Vuelta, unlucky in the WC and Lombardia, could have won both --> my first argument : too short on preparation, his form came 1-2 weeks too late