It's been obvious to me for a while that Berto needs things to go his way to win the Tour. Quintana racing the Giro prior to the Tour is a start. Berto needs to be lucky with Froome slightly off his best form or crashing (not saying I want him to crash). Berto has to avoid crashing and stupid time loss and stay as close to Froome as possible, waiting for a moment of weakness. If he can somehow work over Froome anything is possible. I wouldn't immediately rate Berto below Porte, Bardet, Chaves and a tired Quintana. He could definitely beat all of them if he encounters no issues.
As has been said above he needs to measure his efforts more. Of course we'd all like him to stick to Froome and Porte's wheel on the first MTF but it's not realistic. He can't afford to lose minutes on the first MTF again. Pacing himself he can limit his losses but I'm not sure he'll be able to change his attitude, he's a true racer. So I guess we'll see one or two spectacular implosions from him in July

hopefully they'll happen with the finish inside so the damage will be minimal
What I'm trying to say is, he isn't without chance. Only Froome is without a doubt stronger than him, so he needs to race smartly, bide his time and hope for the best.