Middleton started twelve regular season games and both of Oakland's playoff contests in his only year as a Raider last season. Mo Collins, who couldn't shake a leg injury last year, is expected to compete with Middleton and Adam Treu for the two starting guard jobs.
Treu did such a good job filling in for Barrett Robbins at center that Callahan wants to give Treu a chance to play guard especially if Robbins has fully recovered from the knee injury that sidelined him last season.
The Raiders also announced the signing of defensive lineman Mike Mohring. The former Charger tore the ACL in his right knee in 2000 but returned last season to play in six games. He's a guy who can play end or tackle.
The Raiders also announced the signing of cornerback Terrance Shaw, who was originally a second round pick of the Chargers in 1995. Shaw was the Patriots nickel back last year and Bill Belichick liked using him against pass-catching tight ends. He's a physical player who's had problems staying healthy during his last three seasons.
As the Raiders continue to scour the free agent market, recent visitors to the Silver and Black complex include tight end Cam Cleeland and safety Pat Tillman.