Harrison went undrafted in the 2002 NFL draft , fearing he was too short (six feet) to play linebacker, and too light (240 pounds) to play on the defensive line. A few teams did send him training camp invites. The Steelers signed Harrison as an undrafted rookie in 2002. Harrison spent two years on and off the practice squad for the Steelers, being released three times, and was also briefly on the active roster towards the end of the 2002 season, playing only special teams. Teammate and fellow linebacker James Farrior later told NFL Network that Harrison was so green early on in his career that he would simply “give up” on plays he was struggling on and would even ask the coaches not to play him when he was struggling. Farrior said, "He was a knucklehead that didn't know the plays. We'd be in practice, in training camp, and he might not know what he doing so he'd just stop and throw his hands up and tell (the coaches) to get him out of there. We thought the guy was crazy."He was signed by Baltimore in late 2003, then sent to the Rhein Fire of NFL Europe, but eventually cut by the Ravens. After being cut for a fourth time, Harrison considered not playing anymore. Shortly after, he was signed a fourth time by the Steelers during training camp in 2004 after Clark Haggans sustained an injury in an offseason weightlifting accident. Showing much improvement, Harrison made the final roster and has remained with the Steelers since.sourceSI's Rare Photos of JamesA lot of stuff was left out of the article, James also called Colt “an idiot kid quarterback.”