Geoff Collins ran Mississippi State’s defense for a week. Now he gets to do it full time.

Collins has been promoted to defensive coordinator, head coach Dan Mullen announced Friday.

He had been co-defensive coordinator and linebackers coach since joining MSU’s staff in 2011.

The 41-year-old Collins replaces Chris Wilson, who has been at State since 2010 and in charge of the defense since 2011. Late Friday, ESPN reported that Wilson has been hired as Georgia’s defensive line coach.

MSU’s defense had its struggles this season, especially during a late skid that saw the Bulldogs drop five of their last six games. The season ended Tuesday with a 34-20 loss to Northwestern in the Gator Bowl.

Collins was given play-calling duties for that game because Mullen said he wanted to “try something different" against Northwestern’s uptempo

spread offense, the kind of scheme that had given MSU trouble earlier in the fall.

In fact, Collins was handling the defensive calls during the week of practices leading up to the game in Jacksonville, Fla.

“Geoff is an exceptional defensive mind, and his energy and passion are remarkable,” Mullen said in a statement.

“His experience as a playcaller and previous experience as a defensive coordinator will make this an easy transition.”

Collins was defensive coordinator at FIU in 2010. That defense led the Sun Belt Conference in total defense, scoring defense and pass efficiency defense that year, just a season after being one of the country’s worst units.

Prior to that, he was linebackers coach and recruiting coordinator at UCF, and Collins has also held jobs at Alabama, Georgia Tech and Western Carolina.

Collins will continue coaching MSU’s linebackers.

He was on the road recruiting Friday and not available for comment.

brad.locke@journalinc.com