The Steelers allowed their former running back, Rashard Mendenhall, to leave as a free agent, and, ironically, he was signed by the Arizona Cardinals, the team that released Wells. The Bengals had been rumored to be interested in Wells as well, but he actually makes more sense for the Steelers than he does in Cincinnati. The Bengals already have their between-the-tackles back in BenJarvus Green-Ellis and the Steelers are short on running backs that suit their style.
Wells was a first-round pick by the Cardinals out of Ohio State in 2009, but he has struggled to stay healthy over the last few years. The only full season Wells played was his rookie year and he missed half of the team's games in 2012. Over the last four years, Wells has carried the ball 625 times for a total of 2,471 yards and 24 touchdowns for an average of four yards per carry. His best year came in 2011, when Wells carried the ball for a total of 1,047 yards and 10 touchdowns.
Bringing in a player for a physical is usually a final step before a player gets signed, as long as they're healthy. If Wells is actually healthy, we could hear that he's going to be facing the Bengals twice a year in a Steelers uniform. If he's not healthy, he'll move on.