Who knows if it's true (though I'm inclined to believe him seeing how the rest of the stage went) but Chaves says being in the 2nd group had nothing to do with his legs and was just a mistake.
From the homepage:
Strange though, considering how attentive he's been the entire Giro.
From the homepage:
"It wasn't a question of not having the legs, I just left my guard down," Chaves told reporters afterwards.
"I was too far back when Nibali attacked and the group formed with Zakarin, Valverde and Kruijswijk 500 metres from the top of the climb. I thought the gap would close because there'd already been a lot of attacks on the climb but the group always came back. But the last attack didn't come back. That was the error."
Strange though, considering how attentive he's been the entire Giro.