I said on another post about clay tournaments that, slow Clay surfaces are becoming a territory for big hitters.Why??
Because they can move well,aren't fast,and still got the Cannons weather it's on serve or ground strokes,and as they don't move well the slow surface make it easier for them to get to the balls on time and be just ready to fire the Cannons.That's what happened to Del Potro,Soderling last year and more recently Gulbis.And they are all tall with 2 handers as well.
I do agree Fed and Nadal in best of 5 are tough to beat and I think both will get to the fianls.