The San Francisco 49ers claimed running back Israel Abanikanda off waivers from the New York Jets on Tuesday and also signed former Tampa Bay Buccaneers RB Ke'Shawn Vaughn to their practice squad, according to a source. In corresponding moves, the Niners officially placed both Christian McCaffrey (knee) and Jordan Mason (ankle) on Injured Reserve, meaning they'll be out for at least the next four games. CMC has a PCL sprain and will need six weeks to recover, so his season is essentially over ...