A blue-collar linebacker from nearby Bluefield, West Virginia, Lilly was a three-time All-WVIAC/All-MEC selection in 2011, 2012 and 2013. At the conclusion of his junior season, Lilly was selected as the WVIAC Defensive Player of the Year in 2012 after piling up 126 tackles, 13 tackles for loss, two interceptions and two forced fumbles. His senior season was just as impressive with 118 tackles, seven tackles for loss, five forced fumbles and one interception. Lilly was named to the all-region teams in 2012 and 2013, and capped his career on the Beyond Sports Network All-American Team in 2013. Lilly's 377 career tackles are third in program history while his 30 tackles for loss are eighth all-time at CU. He is also the only player in program history with 10 or more forced fumbles.