The Oakland Raiders signed former Atlanta defensive tackle Vance Walker to a free-agent contract on Monday in the latest move to upgrade a depleted defense. Walker is the sixth defensive free agent signed by Oakland in the past week. He joins tackle Pat Sims and Jason Hunter on the line with linebackers Nick Roach, Kaluka Maiava and Kevin Burnett also added to the mix. The Raiders are expected to bring back only three starters from the defense that gave up the fifth most points in the NFL last season. After addressing the front seven in the first week of free agency, the Raiders now need to work on the secondary, where the only starter from last year under contract is safety Tyvon Branch. Source: Associated Press
