I'm not sure I agree. There aren't that many three set battles for the favorites, just for the players who aren't good on grass.
The best grass courters have all advanced easily: Maria, Lindsay, Kim, Amelie.
The worst grass courters have played poorly: Dementieva, Myskina, Schnyder
The Williams sisters are obviously not playing well at all. The only exception is Kuznetsova who is playing okay but has had a really difficult draw.