http://www.redskins.com/news/newsDetail.jsp?id=5119
i don't think getting a bigger back is the answer (although Rock Cartwright shouldn't have lost that weight, condemned him to special teams).
the answer is whipping the OLine into shape and calling plays that use Portis's SPEED. a toss or sweep from that close with Portis has to be close to 100%. Gibbs keeps going back to this one-dimensional offense even after he's seen what opening up accomplishes