49ers released FB/RB Rock Cartwright. The Niners are stacked with big backs like Anthony Dixon and Brandon Jacobs. Cartwright won't last on the open market long as a versatile back that also excels on special teams.

49ers signed RB Rock Cartwright to a one-year contract. A career special teamer save for two short stints in Washington, Cartwright appeared in 31 games for the Raiders the past two seasons. He's carried the ball only 13 times since 2009. He'll help make up for the loss of Blake Costanzo on the Niners' special teams unit.