No real shock there. Things would become downright boring if Buffy was always the strongest, the fastest, the most skilled fighter in the entire series. There would be no real challenge for her. It would really be surprising if Faith WEREN'T stronger, considering the things that she could do before even being Called. As a thief, in the society in which she lived, she had to be for all practical purposes, an acrobat, a martial artist, a rock (or wall) climber, a marksman, and almost certainly many other things, just to survive and enjoy a certain degree of success. Before Buffy was called, she was a cheerleader. Not a sedentary occupation, to be sure, but certainly less intense on the worst day that anything Fray did on her most quiet days. It stands to reason that, given the differences in their lifestyles before being Called, Fray, who was bigger, stronger, faster, more agile, and, a more experienced fighter, would retain that same degree of superiority as the Slayer.
