Yeah I don't think Froome has poor descending skills at all, but I do think he doesn't like to take risks at descents, contrary to Contador, who doesn't have extraordinary descending skills at all I think, but who doesn't mind going full into a descent at all when necessary, If Bertie can't drop Froome in the descent at least he try to make Froomey feel uncomfortable for the first time this TDF.
Also, Quintana's descending skills are a mystery to me. I used to think he was a good descender because he did a great descent of the Col de Joux Plane in that Dauphine stage he won, but after that he hasn't really shown anything more than normal on descents I'm afraid......
Nibali is the only one who can really make a difference on a descent I think, of the current GC riders. Maybe Contador can do something by being fearless/reckless........