Williams signed a $25 million, four-year contract with Oakland in 2015, but saw his playing time diminish last season. The move made Tuesday saves $4.5 million on the salary cap.
Williams went from playing about half the defensive snaps in 2015 to playing just one-third last season, according to Football Outsiders. He had just 17 tackles and a half-sack.
The Raiders previously lost defensive tackle Stacy McGee in free agency and will likely target that position in the draft.
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