[2] He made his debut in round 8 of the 2018 season against Hawthorn at the Melbourne Cricket Ground (MCG).

[4] At the AFL Draft Combine, he recorded 88 centimetres (35 in) in the running vertical leap and level 21.5 in the yo-yo test.

[6] Sydney coach John Longmire praised McCartin for his work rate during his first preseason.

He played 15 games in his debut season as a key-position forward after Sam Reid was kept out with injuries.

Football manager Tom Harley commented, "For an 18-year-old to hold down a key-position post for more than half the season in his debut year is an unbelievable achievement.