Cadillac Williams, the injury-prone great car-nicknamed hope of the Tampa Bay Buccaneers circa 2005, will be a great fit as a role-playing running back for somebody, and recent mid-lockout NFL rumors scuttlebutt has the St. Louis Rams, who've long looked for somebody to take some of the punishment Steven Jackson currently absorbs by himself, interested in being that somebody.
Williams has returned from a near-career-ending cascade of injuries and ineffectiveness in 2008 and 2009 to deliver two solid seasons for the Buccaneers as a part-time back and occasional pass-catching threat. He's not a traditional change-of-pace guy—Jackson might be more inclined to split carries with a less threatening Darren Sproles type—but he would give the Rams more of a chance to sit Jackson in the roughest situations than Kenneth Darby and Keith Toston offered in 2010.
The main question with any possible running back move, besides the obvious need for the NFL lockout to end, isn't how good the complementary back is—it's how amenable Steven Jackson will be to being complemented. Intuitively, Jackson seems less likely to welcome a time-share with somebody like Williams who was once getting 200 carries a year.