In that stage 9 TDF, the main group was only 33 riders, plus it was a GT, and hence the racing more predictable. The worlds is like a Classic race, you need to be watching all the time and they don't follow such a steady pattern.
Tell that to the GC riders who got caught out!
Agree though that a lot of the GC riders tend to be quite poor at that sort of thing, probably why they have more classics oriented riders looking after them on those stages. Thinking back to when Cancellara led the Schelks through those cobbled stages a few years ago when everyone else seemed all over the place.