Marie-Blanque is also the climb (and descent into Pau) when Hinault famously put 4 and a half minutes into Greg LeMond back in 1986.
The very next day was when Hinault went on a solo break over the Peyresourde, burned up, and LeMond attacked him up the Super-Bagnères, taking back nearly all of Hinault's lead on him, and eventually winning his first Tour.
So it is possible to attack on the Marie-Blanque and put time into people, even with the descent into Pau to finish the stage.
I wonder if Discovery is positioning to attack? The entire team has moved up to the front of the Peleton behind the T-MO guys.