Heupel's coaching career began when he joined Stoops' staff as a graduate assistant in 2004. He spent one year on Mike Stoops' Arizona staff, then returned to Norman as quarterbacks coach and was promoted to his current position in 2011.
Texas coach Mack Brown and Applewhite, though, didn't have as smooth a relationship.
Applewhite was the Big 12's Offensive Player of the Year in 1999, but eventually lost his job to Chris Simms in a controversial decision by Brown in 2001.
Simms started the entire year — including a 14-3 loss to the Sooners — but was replaced by Applewhite in the Big 12 Championship game after four first-half turnovers against Colorado.
Applewhite, then a senior, nearly led the Longhorns to an incredible comeback, and then helped Texas win the Holiday Bowl later that month.
Brown and Applewhite buried the hatchet quickly, though; the former quarterback joined Brown's staff as a graduate assistant coach in 2003, then as a full-time assistant in 2008 after stints at Syracuse, Rice and Alabama.
Interestingly, while Applewhite works to help Brown save his job at Texas through a difficult season, Simms recently joined the chorus of critics.
“I really don't think so,” Simms said in a recent Fox Sports 1 interview when asked if Brown would coach Texas next year. “Unless they went on some miracle run here, but I don't see it. I don't think the talent is there. They have a tough schedule with a lot of tough games. I don't think he will be back.”
A third Big 12 quarterback from that era is also coaching at his alma mater. Texas Tech hired Kliff Kingsbury as its head coach last December.
“It's been fun to watch,” Kingsbury said at Big 12 Media Days in July. “Those guys were obviously great players and great football minds. To watch them come up in the fashion they have has been really impressive.
“I know Josh really well. Josh is one of the smartest football guys I've ever been around. I'm sure Major is the same.”