He was awarded an AFL Rising Star Nomination for his 25 possession game against the West Coast Eagles in round 18, 2002.
[citation needed] McMahon played 18 games in 2003 and established himself as an important member of the Bulldogs' defence, being assigned dangerous small forwards and providing run and rebound.
[citation needed] In 2008, McMahon made a solid debut for Richmond in their Round 1 clash against Carlton Football Club at the Melbourne Cricket Ground (MCG).
McMahon was damaging as he kept finding the football across centre half back with 20 kicks and 12 handballs adding to a total of an outstanding career high of 32 disposals with a brilliant goal from outside 50.
[1] After Terry Wallace was replaced as coach by Damien Hardwick in 2010 McMahon was never selected[2] and also suffered a leg injury.