Who's fault is it?
I guess he told you that he took the penalty because everybody was tired.
Damn, I just edited my post.

Anyway, it's not his fault that he was picked for the penalty. Chiellini was basically dead and Buffon could never take a penalty (can't imagine it

), that leaves Maggio, Giaccherini and Bonucci. Picking one of those three is a lottery, and someone had to do it. I don't blame him for missing it.