RENTON -- The Seahawks added center Kris O'Dowd to the roster, not a shock considering the lack of personnel at that position.

Max Unger is the starter, Lemuel Jeanpierre the backup, but he left Tuesday's practice because of a groin injury. John Moffitt has also worked at center, but he's out for at least the next couple of weeks after undergoing elbow surgery.

The Seahawks have not announced the transaction to determine who was let go to make room for O'Dowd on the 90-man roster.

O'Dowd attended USC. He went undrafted in 2011, and was signed first by Arizona in 2011 and by the Jets this year. Each team let him go.