Cav's major flaw is that he makes it look so easy, that doesn't just happen from team to team to team.
Griepel's pretty much in the form of his life, and isn't going to get a sniff (well maybe one charity win) in the race of the season.
Greipel has been surpassed in the pure sprinter stages by Kittel anyway. It is surely between him and Cav for today.