"Mike and Brent have a long history and comfort level working together, and have together led some great defenses," Bob Stoops said. "We feel very fortunate to have Mike on our staff. Over the past few months, because of the reputation he has built among his peers, he was a highly sought-after coach.
"People across the country recognize his tremendous knowledge of the game and great energy. He will have a very positive impact on our program."
Sooners Illustrated has been suggesting this to be the likely case for a while.
Mike was let go in the middle of this season after a 1-5 start in his eighth year as the Wildcats' head coach.
Just a year earlier, Arizona sizzled out to a 7-1 mark and Top 10 ranking, but the Wildcats lost their last five games and five of their first six this year, including their initial four Pac-12 Conference games.
Losses in 10 of his final 11 games was enough for Arizona athletic director Greg Byrne to pull the trigger on firing him.
Since then, Mike has been sighted on the Sooner sideline for many games, including the Insight Bowl in Tempe, Ariz., where it almost seemed like he was already a part of the staff.
Bob was questioned the morning after OU's 31-14 victory over Iowa about the issue and his comments suggested Mike rejoining the staff was a very realistic possibility, with one exception: there was no room on the staff at the time.
"Well again, in the right circumstances," Bob said. "You never know, and he's got a lot of other good opportunities, so [we'll see]."
The more opportunities Mike passed on, the more it seemed like he was destined to return to Norman.
That's just what happened, as defensive backs coach Willie Martinez resigned.
"Willie has some attractive options and is going to pursue them," Bob Stoops said. "I appreciate all of Willie's work here. He represented our program in the right way and will continue to do well in our profession."
"Obviously, it's very comfortable to come back to Oklahoma," Mike said. "Bob and Brent and I grew up in the profession together and all of that feels very good."
The Sooners hope his return will help shore up a secondary and defense that ranked just 80th in the country during the 2011 season, allowing 241.46 passing yards per game.
An OU defense which has been dominant in recent years finished just 55th in total defense, surrendering 376.15 yards per game.