Mullen attended Wittenberg University in Ohio, where he was a four-year letterwinner and a 1989 All-American selection at defensive back.

After leaving Hawaii, Mullen moved to Ohio University in 1992 as an offensive graduate assistant.

He also coached tight end Ray Thomas and fullback Ovie Mughelli, both whom played professional football.

Mughelli was a fourth round NFL Draft selection after rushing for 12 touchdowns, the most in 30 years in school history.

[1] Mullen coached some of the greatest quarterbacks in school history, including Cory Randolph, Ben Mauk, and Riley Skinner.

Mauk started six games and led the Deacons in passing yards in 2005, before being injured and transferring to the University of Cincinnati during the 2006 season.

On March 1, 2011, Mullen was announced as the new offensive coordinator for the Charlotte 49ers, who began play in 2013.

Four of those 500+ games came against FCS scholarship programs, including 501 at #3/#6 ranked Coastal Carolina.