Vande Velde can be a very good time trialist. He finished 8th in the first time trial and won the Circuit de la Sarthe TT earlier this year. He strikes me as the kind of guy who, properly motivated, could make a huge ride in the second, long time trialer.
Having said that, he's probably not in Evans' or Menchov's league on most days. I think he's going to need to gain some more seconds on both of them in the Alps before that TT. Menchov looks really strong to me right now so I don't know if Vande Velde can do it.