Now Stoops' challenge will be making Kentucky competitive in the conference that has won the last six BCS national championships.
The Wildcats are coming off their third straight losing season and second without a bowl appearance. Seven of their eight conference losses this season were by margins of at least two touchdowns, including a 40-0 blowout at home to Vanderbilt on Nov. 3 and a 37-17 season-ending loss at Tennessee on Saturday.
Stoops has a proven track record of rebuilding defenses, which represents a philosophical shift from the offense-minded Phillips.
Before joining Fisher's staff, Stoops resurrected an Arizona defense with similar issues that Kentucky experienced. Arizona was 109th in total defense before his arrival; the defense was ranked in the top 25 in his final two seasons and Arizona earned consecutive bowl bids.
Stoops leaves a Florida State program poised to claim a BCS bowl bid if it wins the ACC championship on Saturday. The Seminoles enter the ACC title game with the nation's seventh-ranked scoring defense, allowing 15.1 points per game.
Fisher said it's a compliment to the defensive players at Florida State that Stoops "got the shot because of how they played and how he coached them."
"I'm very proud of him. Very happy for him," Fisher said after Florida State's practice Tuesday. "He got an opportunity to go on and further his career and it's something he wants to do. ... We wanted Mark to stay here for a long time until he got what he wanted to do. Our players are very elated. They know that that's part of this business."
Florida State defensive end Bjoern Werner said the players are also happy for Stoops.
"Everybody knew he wanted a head coach job," Werner said. "Everybody was happy for him. Nobody was like sad that he was leaving. ... He did everything he could. He turned a great defense into an even better defense."
The search for Stoops' successor will begin next week and Fisher hinted that it could be an internal hire.
"There are possibilities of that all the time," he said. "We have some great coaches underneath."
AP Freelance Writer Bob Ferrante in Tallahassee, Fla., contributed to this report.