They say Shanahan screws fantasy owners, because he usually goes with a Running back by committee.
But that's only because he hasn't found a real every down back since TD. Someone who can catch out of the backfield, block on passing downs, run in open space, get the short yards, power in for a TD, run the stretch.... etc...
Clinton Portis was the closest thing he's had since, & Travis Henry is similar, IMHO.
Obviously, I'm not a head coach, but if I were in Shanahan's shoes, Mike Bell would be in the game inside the 20.. that is if he's still healthy, I really don't know.
Selvin Young is a good runner, and may be the starter before the end of the season, if he can show he can do all those other things.