Dan Mullen has given Mississippi State consistent leadership. But he hasn’t been able to stabilize the coaching leadership of his defense.

Bulldogs defensive coordinator Manny Diaz left for the same position with the Miami Hurricanes, forcing the coach to find his third new defensive coordinator in as many seasons. It will also be the Bulldogs’ sixth new defensive coordinator in the last eight years.

The revolving turnstile makes Mullen’s job much tougher. What’s ironic is that Mullen’s string of successful hires for the position has been a major factor in the instability. Defensive coordinators have left for more prominent programs.

Diaz is a Miami native, so taking the job with the Hurricanes makes sense. But this isn’t the first time Diaz has left Mississippi State. He was the defensive coordinator in 2010 before leaving for the same position at Texas the next season.

Diaz reportedly owes Mississippi State $265,000 for leaving.

Geoff Collins left after the 2014 season. He coordinated the Bulldogs defense for two seasons before leaving for the same position for less money at Florida. An upset Mullen described Collins’ decision a lateral move.

It wasn’t a lateral move. Florida has eight SEC titles and three national titles in the last two decades. Texas owns an incredible 32 conference titles and four national championships.

Mississippi State hasn’t won an conference championship since 1941 and has never captured a national title.

Leaving for a more successful program would make sense. But at least one of Mullen’s defensive coordinators — Carl Torbush — left for a less-prestigious program.

In between Diaz (his first stint) and Collins, Chris Wilson coordinated the defense for two seasons. He left for Georgia accepting the position of defensive line coach.

Mullen’s first defensive coordinator, former North Carolina head coach Torbush, departed after one season to be defensive coordinator at Kansas, which won only five games over the next two seasons.

That probably isn’t the most bitter departure for Bulldogs fans. For that, we return to Diaz. Last year, he reassured Mississippi State fans that it would be a longtime before the defensive coordinator position would be open again.

It was a classic example of a coach getting caught up in the moment and saying more than he should. Although it may have been true at the time, Diaz should know that life sometimes presents unexpected opportunities.

But to be fair to Mississippi State, coaching changes are a fact of football. Successful coordinators move on and unsuccessful ones are fired. It isn’t a position most coaches keep for life.

Kirby Smart was the longest-tenured coordinator in the SEC at eight years before he finally moved on to be a head coach at Georgia. Ole Miss’ Matt Luke and Dan Werner are now the longest-tenured coordinators in the SEC at four years. More than half of the coordinators in the conference in 2016 will either be in their first or second season.

Still, Mullen’s next hire at defensive coordinator is important. He needs to find a coordinator who will stay long enough to help the Bulldogs continue their progress.