Problem is, Rivera knows McD's defense inside and out, and he has Cam Newton to take advantage of Bills weaknesses.
i don't think there's an advantage.
Except there isn't much film on what he's doing differently now as his own HC, tweaks made to fit the new players and how they work within the scheme as well as what wrinkles Frazier has added.
Meanwhile I believe McDerm knows panthers playbook and personnel inside and out.
I definitely give him the advantage in the department. How big a factor it is in the game remains to be seen.