At the very least he'll be a veteran presence in that backfield.
Can he still play, and how well? Even if he's lost a step and can't cover as much ground as he used to, he'll be a heavy hitter/enforcer type that is definitely needed in our secondary. He'll be able to step in and play without a lot of adjusting to the system, albeit the system has evolved since he left.
He'll ned a lot of pre-season snaps to find his place and for the others to adjust to his presence - at least that's what I hope. I look forward to seeing him in action.