First off, I would demand that we work on switching the placement of the ball.. he is a runner that leaves it his right arm no matter what.. one of the first things a player is taught is to keep the ball away from contact. With him being such a violent runner.. it is probably even more important for his ball security.
Second, I think I would take a fundamental look at how he carries it.. as mentioned above.. he exposes a little too much of his cradle while carrying the rock. As a opposing defender, that is the first thing I would focus on beyond his hips.
Third, and probably a little over looked is the sleeve that he wears.. more of a rubber texture to it.. as the game progresses and sweat is expelled, I think there is an opportunity for that sleeve to become slick..
I would not over tinker with his running style.. he is the most physical back to come into the league in a long while.. makes him the player he is..
But as in almost any player.. there are some things that could be improved upon.. his is his hands and ball security.
"The oranges are dry; the apples are mealy; and the papayas... I don't know what's going on with the papayas!"