Williams (foot) reverted to the Cardinals' practice squad Monday, per the NFL's transaction report.
Williams made an early exit from Sunday's loss to the Ravens late in the second quarter and was unable to return, finishing Week 8 with two carries for five yards and one catch (on one target) for four yards. Arizona has elevated him three times from the practice squad, so the team must sign him to the active roster in order for him to be a part of its backfield. Having said that, Williams' health might prevent that from happening in the short term.