Free agency isn't meant to build championships. It never has been; otherwise teams like the Washington Redskins would have three Super Bowls already in the 21st century. Teams like the Dallas Cowboys would have at least one Super Bowl appearance since 1996. There's a reason many experts firmly grip the theory that you build championship teams through the draft, not free agency.
Many of the players available are largely available because their original teams didn't believe they were conducive towards the construction of a winning team; either over-valued worth, attitude, talent or threat to team chemistry. Granted there are the exceptions to the idea, in which a single player obtained through free agency has pushed a team into the realm of championship contender. Two of the more recent examples includes quarterback Drew Brees, who was signed by the New Orleans Saints in 2006. Yet it wasn't until his fourth season that the Saints won the Super Bowl. Defensive back Charles Woodson signed a seven-year deal worth $52.7 million with the Green Bay Packers in 2006. It wasn't until his fifth season that the Green Bay Packers won the Super Bowl.
Yet these examples aren't good examples. Reason being is that both teams also used free agency to find third-string tight ends, backup centers, special teams players that helped build the roster from the 40th-53rd spot; areas that are exponentially better for teams that annually make championship runs. The Pittsburgh Steelers and New England Patriots won five of the previous ten Super Bowls. Neither team is known for signing big-time free agents, choosing to build their rosters in-house with several free agent signings to complete the roster.
Now one could argue that the Bengals in free agency isn't a success because they're largely signing players as a response to issues outside of their control. Nate Clements wasn't signed to add depth at cornerback. He was signed as a measured response to replace the departed Johnathan Joseph. Keith Rivers had wrist surgery and Cincinnati signed the combination of Thomas Howard and Brandon Johnson. Roddrick Muckelroy suffered a season-ending injury and soon after, the Bengals signed outside linebacker Manny Lawson.
We also fully acknowledge that free agency could, and maybe should, be argued as a success. Even though their reacting to losing players, they are adding depth in the meantime. Since Keith Rivers got hurt, weakside linebacker improved with two quality players. Muckelroy's injury opened the door for a productive veteran at strongside linebacker. Signing Clements makes the Bengals immediately better, even if Joseph would have stayed. Max Jean-Gilles is a veteran backup guard that could be a future starters and Bo Scaife adds an element of veteran leadership to a position that's young and inexperienced.
The Bengals will react to available players on the market, deciding if it helps bolster the overall roster on this team. Signing backup players is just as critical as starters. On any given player you could lose a key starter for the rest of the season with a significant injury. Now your backups suddenly become starters. And for guys with a history of injuries like Jermaine Gresham, or Chase Coffman, having an insurance policy like Bo Scaife definitely helps the overall product of this roster. And that is what free agency is about.