I even think contador should just stick with froome and let froome comes back. Clearly purito and valverde have no interest of distancing Froome, but more about chasing bonus point. If contador sticks with them, and let them sweat it out when Froome comes back, contador can just follow wheel and conserve energy to fend off the sprint at the end. He clearly has more in the bank with the fact that he had accelerated to drop froome several times. While purito tried, valverde pretty much did nothing.
If Purito wants to win, he has to distance Froome. And If Valverde wants to win he has to distance froome. But valverde never shot for the star. He is a podium chaser. And his tac tic is very clear. Wheelsuck to the gill and sprint for bonus. If contador keeps Froome close, he should be able to handle valverde.
Of course it's easier said than done.

But today, it's clear the intention of valverde and purito. Froome is dangerous man. But contador seems to be too concern for Froome and not seeing valverde is closing in. Reminds me of Andy. Worrying about Contador and not paying attention to Cadel.