Mullen ran the same offense he ran at Florida with Lee at QB most of the season. He didn't really adjust the offense to fit Lee's talents, he had Lee and to some extent Relf, run his offense. I don't see him changing that, and in fact everything he has done (recruiting a mobile Juco QB and recruiting a mobile HS Qb) show that he is going to stick with his offense, which is a run first offense, and the QB needs to be more than just mobile, he needs to be a running threat.
I have no idea if Russell can be that threat, he may be a better runner than Relf, so lets not this thread turn into a pissing match about how great Russell can be. From everything I have seen about Russell he looks like a pocket passer, and the fact that Mullen is going all out for Newton tells me that he doesn't want Russell starting the next two years.