Nadal was fully peak on clay and grass in 2007.No, 1) the entire period is 2004-2009, check the original post(which is already too little for calling it "an era") 2) even in the shorter period you are proposing, his main rival had positive head to head against him and winning streaks you were mentioning(which Federer he did not have against him) 3) he beat still developing Nadal on grass, in 5 sets, the following year he was beaten there too.
Yes, Nadal was developing, but Fed met him many times on clay where he peaked early so it was impossible to have a winning streak over him because of that.
8-6 is a very marginal lead. Close to even. Fed was only dominated in 2008-early 2009.
Nadal back then was still a solid rival to Fed on clay and grass, who cares if he was developing. You talk as if he was chopped liver.