When Josh Heupel returns to Oklahoma this season as the Sooners kick off SEC play against Tennessee, it’s sure to bring up plenty of memories for both sides. Most will be fond ones of his time as a player and leading OU to a national title in 2000, but there’s also the elephant in the room. Before breaking into the head coaching ranks, Heupel was a quarterbacks coach and later co-offensive coordinator at his alma mater under his former head coach, Bob Stoops. But Heupel was fired ahead of the 2015 season after nine years on Stoops’ staff coming off of an 8-5 season. He made no secret about the…