O'Neil was hired by then-49ers head coach Chip Kelly on January 26, 2016. He was not retained when Kyle Shanahan became the head coach in February of 2017. This will be O'Neil's first coaching job since being let go by the 49ers.
Under O'Neil, the 49ers defense was historically bad. It was last in the league in total and rushing yards allowed, last in points allowed, and 19th against the pass.
O'Neil also spent time on the coaching staffs of the Cleveland Browns, Buffalo Bills, and New York Jets.
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