Now, this. The interesting thing about this phase of Jones' career is that the abilities which allowed him to give up the fewest yards per target in 2006 (5.4 YPC on 69 targets, according to Football Outsiders' metrics) were pretty much shot during his time in Dallas. Jones looked slow and out of place with the Cowboys, allowing 6.4 yards on 51 targets. After that lost 2007, Jones' passes defensed dropped from 14 to 9; his interceptions from four to zero. And he showed none of the dynamic return ability that also typified his Tennessee career.
The move is low-risk for the Bengals from a financial perspective -- it's a veteran minimum flyer with incentives (and certainly language allowing the team various out clauses in the event that Jones can't stay out of trouble). How Jones might meet those incentives, even if he's able to regain any percentage of his former skill set, is unknown. In Leon Hall(notes) and Johnathan Joseph(notes), the team already has one of the best cornerback tandems in the league - unless there's an injury, Jones would be a nickel guy at best. Perhaps there's some room in the return game, but this looks like a depth signing - the kind the Bengals do all the time. They'll bring troubled players in on short deals, hoping they can help, but it's a "churn-‘em-and-burn-‘em" game for the most part. All Jones can do is keep his nose clean and seize the opportunities on the field when they present themselves. He'll also have to forgive the skepticism regarding the notion that he's capable of either act at this point in his life.