Brady is running it. Josh sends in plays and then based on personnel grouping (which has been improved flexibility wise as a base) and what defense is showing Brady has the responsibility of getting them out of a bad play and into a better one. BOB and Tom were not working with 3 viable TE's consistently or as dynamic a lead RB (who fumbled his way off the active list late last season) and they didn't have a weapon like Lloyd on the perimeter. Josh at this point in his career is probably a more dynamic OC than BOB was, but absent the weapons he struggles or he wouldn't have been available to return here. BOB and Tom had a limited offense in 2009, one in transition in 2010, one developing but still missing a couple of consistently dynamic weapons in 2011. Josh has inherited the full monty in 2012.
Not to mention the ability to play in front of a much improved defense as opposed to the defenses in transition between 2009-2011.