I was very happy with AD's play before he hurt his ankle, and well worth the money the Pats paid to get him. Indeed he was everything that was advertized - flexible, athletic, fast and smart.
The injury certainly slowed him up, but I suspect that the coaches are holding him back at the moment trying not to stress the ankle. I get the impression that BB is carefully herding his team for the playoffs, because I get the same feeling with Maroney. Dont play either of them too hard or too many times in the earlier part of the season, and then spring them in the run up to the playoffs and beyond. After all the team is doing just fine with them in low gear so why push it? The advantage in December/January is that they are still fresh, the opposition has no film on how they affect defensive and offensive plays, and they are just bursting to contribute to one of the greatest teams of all time.
We know that AD and Maroney have all the necessary skills, ambition and the temperament; we just have to be patient until Bill, Dan and Josh are ready to unleash the beasts!