Cox was one of San Diego's big free agent acquisitions a year ago, signing a four-year contract for about $20 million, with about $10 million guaranteed. But he struggled and was benched three times in four games.
McClain played in 34 games for the Chargers the last two seasons, with 25 carries for 74 yards and 10 catches for 22 yards.
Patrick started four of the 13 games he played in 2013, recording 36 tackles and an interception. He ended the season on injured reserve with an ankle injury.