It is interesting to note that when James Cook was drafted, it was always mentioned that he was the younger brother of Dalvin Cook. Dalvin was the more distinguished player in college, but his career in the NFL is characterized by frequent changes of teams (IIRC, at the moment he is on the Cowboy's PS). When healthy, he seems to be a rather competent RB, but there has not been a single season where he was not injured.