I do respect the traditional clay motif & like to watch it. But the outcomes this year do not support that speculation. The "sliders", even Schiavone who is arguably the best, did not distinguish themselves at RG or even throughout the clay season.
I rarely treat with this "what-if" kinda thing but: There is not the slightest doubt if Masha had not slipped up versus Li Na, she would have dismissed Francesca--with her game just as it is. 
"That's the way the world works... right now." --Maria Sharapova at 17