George Godsey -- OC(?)
Brian Ferentz -- OL
Stan Hixon -- WRs
Charles London -- RBs
Anthony Midget -- Safties(?)
Craig Fitzgerald -- Strength & Conditioning
John Butler -- CBs(?)
Bill Kollar -- DL
Jim Bernhardt -- QC
Here's an overview of those four coaches' résumés:
Butler: Has been a college assistant coach since 1995, beginning at his alma mater Catholic University. He was a graduate assistant at Texas, then worked at Midwestern State, Southwest Texas State, Harvard, Minnesota and South Carolina before joining O'Brien's staff at Penn State as the defensive backs coach. A year ago Butler became the defensive coordinator.
Hixon: Started his coaching career in 1980 as an assistant at Morehead State. He spent 24 seasons as a college assistant before becoming an NFL receivers coach. That job came with the Washington Redskins in 2004 until the end of the 2009 season when he was out with a head coaching change. Hixon then coached receivers with the Buffalo Bills for two seasons before joining O'Brien's staff as receivers coach and assistant head coach.
London: Served as a graduate assistant at his alma mater Duke in 2004 and 2005 before becoming the running backs coach. He then spent three years as an offensive assistant with the Chicago Bears and a year as a scout for the Philadelphia Eagles. Before joining O'Brien's staff as the running backs coach, London was an offensive assistant for the Tennessee Titans.
Midget: Graduate assistant at Virginia Tech before coaching at Georgia State where he was a defensive coordinator in 2012. He joined O'Brien's staff as safeties coach last year.