Shirley was redshirted during the 2003 season. He played in eleven games in 2004, mostly as a rotating defensive lineman, making 16 tackles, with 2.5 for loss -- he also recorded one sack. Shirley started the first five games of the 2005 season before he was sidelined by an injury, recording 14 tackles with four for loss and adding one sack. He bounced back in 2006, starting all of the team's twelve games and recorded a career best 22 tackles with 4.5 of them for loss and also making two sacks. His 2007 campaign was cut short by suspension and injuries. Nevertheless, Shirley was invited to play in the Hula Bowl and the East-West Shrine Classic after the season. A massive clogger inside, Shirley is a true two-gap player. He is big and strong, but is also agile and has good speed for the position (5.10-40). He moves well in crowded spaces and uses his hands well. He does have some pass rushing skills, but has a limited range. Shirley needs to show more competitiveness, and he lacks consistency. He should have dominated at his level, but he is not overly athletic. Stamina is a big concern and he has struggled with injuries and off the field issues. The massive Shirley was once headed for the mid rounds, probably as high as the third; but injuries and off the field issues have clouded a once promising career. If he dedicated himself to the weight room and acquire a sense of urgency, Shirley could develop into an effective run stuffer. His rare pass rushing skills should also help him at the next level. There's no questioning Shirley's talent, but he is surrounded by many questions. A team might would take a chance on him late.