Most of the assistant coaches Bill O'Brien brought to Penn State are leaving the school with him to take jobs with the Houston Texans.
Four assistant coaches and eight total members of the staff submitted resignations Monday, including defensive coordinator John Butler and strength and conditioning coach Craig Fitzgerald. Receivers coach Stan Hixon, running backs coach Charles London and safeties coach Anthony Midget also resigned.
All of them are expected to join O'Brien's staff in Houston, along with strength coaches Dwight Galt IV and Sean Hayes. Jim Bernhardt, a special assistant to O'Brien and the coach's right-hand man at PSU, also resigned to go to Houston.
Penn State now has only three coaches remaining on staff: interim head coach Larry Johnson, offensive line coach Mac McWhorter and tight ends coach John Strollo. Those three will have to handle all recruiting and administration duties until a new coach and staff are hired.
Perhaps the biggest loss among the assistant coaches is Fitzgerald, a very popular figure among the players who installed a new, modern weightlifting program for the team built around free weights. The previous strength coach relied primarily on machine lifting.
Fitzgerald also won over the players with his ultra-energetic personality and gung-ho approach to working out. He would wear shorts and short sleeve shirts even in frigid temperatures on game days and would motivate the players shortly before kickoff by doing worm-like up-down drills.
Butler departs after serving as defensive coordinator for one season, and it produced some of the worst defensive results in Penn State history.
The Lions had the worst defensive game since the 1800s when they allowed 63 points and 686 yards of offense to Ohio State on Oct. 26. That was the last of three consecutive games in which PSU allowed more than 40 points, which also hadn't happened since the 1800s.
The defense did play better toward at end of the season, but Butler's unit finished the season allowing 26.2 points per game.
Butler was the defensive backs coach his first year at PSU, and O'Brien made him the defensive coordinator after Ted Roof departed for Georgia Tech following the 2012 season.
There were no major developments in the PSU coaching search Monday. Vanderbilt coach James Franklin is expected to interview with the Washington Redskins and Cleveland Browns this week, while Johnson reportedly will get an interview with the Penn State search committee.