On Dec. 21, 2020, Sonny Cumbie left his job as offensive coordinator at TCU for the same position at his alma mater, Texas Tech.

A little more than 12 months later, Cumbie will be the Red Raiders’ head coach for one final game — the Liberty Bowl against Mississippi State on Dec. 28 — while already hired to a permanent job elsewhere.

What a difference a year makes.

“I’m going to try to write a little book about it after it’s all said and done,” Cumbie said Sunday.

Cumbie became Texas Tech’s interim coach on Oct. 25 when the school fired head coach Matt Wells. He was retained when Joey McGuire was officially hired Nov. 8 as the Red Raiders’ new permanent head coach, but with McGuire still an assistant at Baylor, Cumbie continued to lead the team.

And on Nov. 30, Cumbie got his own permanent gig as the new head coach at Louisiana Tech.

But he wanted one more game with the Red Raiders before departing, and he’ll get it against the Bulldogs in Memphis.

“I feel like I owe it to these players from Texas Tech as well to give all of us the best chance to win a football game,” Cumbie said.

Cumbie worked out the arrangement with Louisiana Tech athletic director Eric Wood and Texas Tech AD Kirby Hocutt, allowing him to coach the bowl game for the school where he once starred at quarterback.

In 2004, Cumbie led the nation with 4,742 passing yards, threw 32 touchdown passes and outdueled Cal’s Aaron Rodgers in the Holiday Bowl. That standout season came under none other than Mike Leach, the former Tech coach whom Cumbie will face with the Bulldogs in less than three weeks.

Cumbie mentioned the wild, varied quarterback meetings Leach held in Lubbock, with topics ranging from pirates to Geronimo to history to pretty much anything.

He said facing his old head coach will be “a lot of fun,” but he acknowledged the game’s outcome won’t have too much to do with the men on the sidelines.

“It’ll be an exciting challenge,” Cumbie said. “But unfortunately for both teams, coach Leach and myself, neither one of us is going to take a snap on the field. It’ll be determined by the players. It’ll be about them and our preparation and the excitement to be there.”

Mississippi State, at least, expects Texas Tech to be well prepared. Bulldogs defensive coordinator Zach Arnett highlighted the Red Raiders’ final regular-season game, a mere 3-point loss to eventual Big 12 winner Baylor.

Tech finished 6-6, including a 38-21 win in Week 1 over Houston — which won its next 10 games — while Wells was still the head coach and Cumbie was running the offense.

“Coach Cumbie did a tremendous job as the offensive coordinator and then as the interim head coach,” Arnett said.

Cumbie now will face one final test in the Bulldogs, a team that got better as the season went on and beat four teams that spent time in the top 25.

“It’s a unique opportunity for all of us,” Cumbie said. “Our players are very deserving of this reward. They’re going to be excited about the challenge of playing Mississippi State and playing against coach Leach. It’ll be a lot of fun.”

And it will end a momentous journey for Cumbie back at his old school before his new job in Ruston, Louisiana, awaits.

“He knows it’s one special ride that we have left with the Red Raiders at Texas Tech,” Hocutt said.

Theo DeRosa reports on Mississippi State sports for The Dispatch. Follow him on Twitter at @Theo_DeRosa.