Originally from Gisborne, Victoria, Hannan failed to make the Calder Cannons and Bendigo Pioneers sides in the TAC Cup before leaving his junior club, Woodend, to join the St Bernard's Football Club in the premier division of the Victorian Amateur Football Association. He won a premiership with the club in 2015 and was named the best player on the ground in the grand final, winning the Jock Nelson Medal. He played four matches for in the Victorian Football League in the same season, before playing solely for the club in the 2016 season. He rose to prominence during the season when he took a "ripping specky" during the opening round match against the, which was described as "Gary Moorcroft like", whereby Moorcroft's 2001 mark is considered one of the greatest VFL/AFL marks in history and the best by ABC journalist, Dean Bilton. Playing fourteen matches for the season, his performances in the final month led to Footscray coach, Ashley Hansen, declaring he had the potential to be drafted to the AFL. He was pivotal in Footscray's semi final win against according to Maribyrnong Leader reporter, Tim Michell, where he kicked three goals in the final quarter and "came to life in the last term to inspire his side". He played in his second premiership in two years when Footscray defeated the by thirty-three points at Etihad Stadium in the VFL Grand Final.
AFL career
Hannan was recruited by the Melbourne Football Club with their first selection and forty-sixth overall in the 2016 national draft. A shoulder injury halted his pre-season and he was considered unlikely to make his debut early in the season. He did not feature in any matches during the JLT Community Series and despite this, he made his debut in the opening round of the 2017 season in the thirty point win against at Etihad Stadium, in which he kicked two goals. He played the opening four matches before he was omitted for the round five match against at the Melbourne Cricket Ground, and missed just the one match, returning for the thirty-eight point win against at Etihad Stadium. In his eighth AFL match, he kicked three goals and recorded fourteen disposals and five marks in the fourteen point loss to at the Melbourne Cricket Ground in round nine to be named in AFL Media's team of the week. He played every match until the round twenty game against at UNSW Canberra Oval, before returning for the last three matches of the year to finish with twenty games in total in his debut season. At the end of the season, he was the Melbourne nominee for the AFL Players Association best first year player award and finished fourteenth in Melbourne's best and fairest with 216 votes.
