The youngest player in the competition when he debuted in 2018, McCartin had 34 games behind him before his teenage years were over. Originally a forward from the Geelong Falcons, he was remade as a key defender in 2021 and has anchored the Sydney Swans' backline since, reaching 150 games in Round 22, 2025. He has played 173 AFL games and kicked 31 goals.