Jimmie Ward questionable, Perrish Cox probable for Sunday

Three 49ers defensive backs are questionable for Sunday’s matchup at Denver, per the club’s injury report. Rookie defensive back Jimmie Ward, a key part of the club’s “sub” packages, might be most questionable of all after missing a third straight practice Friday because of a quadricep injury. Cornerbacks Tramaine Brock (toe) and Chris Culliver (shoulder)…