Cornerbacks -- Ron Bartell(notes), St. Louis Rams/Brandon Carr(notes), Kansas City Chiefs
According to STATS, Inc's data, only five cornerbacks with 50 or more targets had a lower Burn Percentage (completions allowed) than Bartell's 45% (45 out of an even 100). Those five cornerbacks happened to be Darrelle Revis(notes), Stanford Routt(notes), Antonio Cromartie(notes), Tramon Williams(notes), and …. Brandon Carr.
One of the reasons that the Chiefs were the AFC's surprise team last year was that their secondary really stepped up. Carr was the forgotten man as everyone started talking about Brandon Flowers(notes) and Eric Berry(notes), but per those numbers (and only sometimes covering the other team's #1 receiver, it must be said), Carr was the most effective man in that defensive backfield.
Bartell was Mr. Unlucky in one department. Effective as he was against the pass and the run (per FO's metrics, he was the Rams' best run-stopping cornerback as well), he didn't get a single pick in 2010 — just 12 deflected passes. Carr had Bartell beat, there — 24 deflections and just one pick. Moral: When you're looking at cornerbacks, don't let interceptions be your ultimate guide when it comes to effectiveness.