Johnson, Utah's winningest quarterback in history with a 26-7 record, became the youngest offensive coordinator in the Football Bowl Subdivision when coach Kyle Whittingham appointed the then 24-year-old to the position in 2011.
However, Johnson's time as a coach hasn't gone smoothly as Utah's offense has failed to be the dynamic force Whittingham envisioned. Johnson served as the co-offensive coordinator last season along with Dennis Erickson, then was demoted to quarterbacks coach when Whittingham hired Dave Christensen as Utah's new coordinator in December.
Mississippi State had an opening since offensive coordinator Les Koenning left to join Charlie Strong's staff at Texas. Mullen is 36-28 since he was hired as Mississippi State's coach in December 2008.
Johnson did not return messages left on his phone.