Tony Moss of The Sports Network has a list of the top five game changers at defensive back. The criteria is a defensive back on a new team, whether that be via free agency or the draft.
1. Eric Berry, S, Chiefs (rookie, Tennessee)
Like [Earl] Thomas, Berry has the versatility to line up anywhere in the secondary, though he projects long-term as a playmaking safety in the Ed Reed, Troy Polamalu mold. Like Polamalu, the 5-11, 200-pound Berry is a fearsome hitter. Like Reed, Berry is a menace when he gets the ball in his hands, and could help out on returns in addition to his work on defense. Wherever new coordinator Romeo Crennel chooses to line him up, Berry is already the face of a Kansas City unit that will be looking to far surpass its 2009 rank of 30th in NFL total defense.
Strong words before he lines up but I agree he'll be a big part of the Chiefs defense in year one. The Chiefs were devoid of talent at safety so he steps in and will likely be the best of the bunch. But to suggest he'll be the number one game changer for all defensive backs might be a little much. He'll have to prove he's immediately better than Rolle or Robinson.
(H/T KC Chiefs Blog)