If it is truly the same finish as last year (can anyone else confirm) then I'm not seeing whatever it is you're seeing.
Here's the finish of the same stage last year:
http://www.youtube.com/profile?feature=iv&annotation_id=annotation_59487&user=CanalF10#p/search/4/Tqj0UJDxptk
There was a slight bend with a couple kms to go, but even in the wet the pavement was fine and there was nothing especially difficult about it.
This was a true mass sprint, won by Greipel ahead of other pure sprinters in a true bunch kick. That finish certainly would not have favored Sagan and I don't think he could have top 3'd a sprint like that. Obviously thats a year ago and a very different race, but if tomorrow's finish is indeed the same, I can't see Sagan getting the bonus he needs in the sprint.
Hard to look past Kittel for the stage win if that's the case.