Charlie Strong, just fired from Texas after a dismal 16-21 record in three years. Strong has been a head coach before, posting a 37-15 record at Louisville, with three bowl wins, including the Sugar Bowl. Strong was previously a defensive coordinator.
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Mark Helfrich, just fired from Oregon after posting 37-16 record in four seasons in Eugene (including a trip to the national championship game), but lost 8 of his last 10 games with the Ducks. Helfrich has no other head coaching on his resume, but was a fine offensive coordinator for Oregon under Chip Kelly.
Helfrich has the higher rise, obviously, taking Oregon to the national title game, but arguably also has the lowest fall with his 4-8 mark this season, since a Texas win at Kansas would have sent the Horns bowling this year.
Both men are accomplished coordinators, albeit on different sides of the ball and both have had past success as head coaches, with a major bowl win on their resume. Near as I can tell, neither man has been connected to any sort of scandal or off field issue, and there will be plenty of jobs open here very soon.