Mack Brown addresses North Carolina's constant defensive coordinator changes Posted Jan 23, 2024 North Carolina Tar Heels football head coach Mack Brown hired a new defensive coordinator for the third time since returning to Chapel Hill in 2019, parting ways with Gene Chizik and naming Geoff Collins as his new defensive playcaller. The defensive coordinator job for the Tar Heels has become somewhat of a revolving door lately under Brown. (On3.com)