Cardinals running back Ryan Williams is a healthy scratch for Sunday's game against the Rams, reports Fox Sports 910. Williams was not on the injury report, though he dealt with knee problems in the preseason.
Coach Bruce Arians said last week that Williams was back to "full speed" and it sounded like he'd back up Rashard Mendenhall. With Williams out, rookie Stepfan Taylor likely will fill that change-of-pace role.