BUFFALO, N.Y. — Buffalo Bills coach Rex Ryan has hired his twin brother Rob to become a member of his staff.

Rob Ryan will serve as assistant head coach with a specific responsibility for defense, the Bills announced Sunday night. It marks the second time the two have worked together after previously serving as assistants on their father Buddy Ryan’s staff in Arizona in 1994 and ‘95.

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What’s unclear is where Bills current defensive coordinator Dennis Thurman fits in the team’s hierarchy.

Rob Ryan was available after being fired as the New Orleans Saints defensive coordinator in mid-November. He was dismissed with the Saints defense ranking last in the NFL in yards and points allowed.

The Bills defense struggled in adapting to Rex Ryan’s system in his first season in Buffalo.