Port Adelaide experience (1998) Following their entry into the AFL in 1997,
Port Adelaide drafted Harley to the club as part of their zone selections, which entitled them to recruit uncontracted players from the
South Australian National Football League (SANFL) prior to the 1996 National Draft. He struggled to break into the Port Adelaide senior team, and often found himself playing in the SANFL reserves for
Norwood during the
1997 season, where he helped the team reach the SANFL reserves Grand Final, where they were defeated by
Port Adelaide. His consistency throughout the year, during which he played in all club fixture games for the first time in his career, was rewarded when he won the club's Most Determined and Dedicated Player Award. and was also chosen to help improve communication links between players, coaching staff and the board of directors. Harley helped the team compile an 18–4 win–loss record at the conclusion of the home and away season, earning them their eighth
McClelland Trophy and securing first position on the ladder leading into the
finals series. Harley led the defence to the number one defensive record in the league during the season, by letting only 1664 points be scored against them. during the season for the second consecutive year. As a result, he struggled to contribute for the rest of the game as Geelong lost to Hawthorn by 26 points. Harley missed the first six rounds of the 2009 campaign with a knee injury, before returning to feature in fourteen games for the year. Despite Harley's injury-riddled campaign, Geelong finished the home-and-away campaign in second place on the ladder with an 18–4 win–loss record. Following the failure of 2008, Harley suggested that the club had learned that it needed to "just be the best team in September" Harley retired as one of the most successful captains in Geelong's history: during his three years as captain, Harley led the club to a club-high two premierships—equalling the accomplishments of
Fred Flanagan—and compiled a 49–7 win–loss record. His legacy at the club was pronounced by Thompson as being "one of the great captains in the history of the Geelong Football Club". ==After retiring as a player==