In the early stages of the Niners' training camp, Pro Football Weekly hears that rookie free-agent RB Kory Sheets has looked better than third-round RB Glen Coffee, displaying a lightning-quick ability to get to the outside. Sheets' emergence could signal the end of the line in San Francisco for the forever-promising RB Thomas Clayton, a player team insiders believe could quickly become a hot commodity on the waiver wire if the Niners release him.