It seriously looks like he's bulked up since preseason. Remember how Matt had such a tough time keeping weight on and would bulk up in the offseason and then would be really skinny again by the end just due to the massive amounts of aerobic activity he'd put in during the season? I think that was one thing that contributed to him getting hurt (which typically seemed to happen late when he was lightened up a lot... hence the coaches asking Whitehurst to bulk up, which he refused to do for fear it would impact his modeling career).
I think Rusell gets every nuance of what is needed out of a QB, including staying big for the end of the year to protect against injuries and to maintain that fourth quarter edge which is desperately needed if you're going to be a playoff team. I am not trying to go overboard on the Russ Love. He just genuinely looks bulkier than preseason, and if that's the case then good on him.