He made his debut for West Coast the following season.He established himself as the team's first-choice full-forward, leading the goalkicking for six consecutive seasons between 1989 and 1994.
Sumich played in West Coast's 1992 and 1994 premiership sides, before retiring from AFL football at the end of the 1997 season.
In 1998, he was co-captain of South Fremantle, and led the club's goalkicking in what was his final year of playing football.
Originally playing for the Cockburn Junior Football Club, Sumich represented the Western Australia Under-18 team which won the 1985 Teal Cup.
[5] Against Footscray in round 13 he kicked 13.3, surpassing his previous record for most goals in a game (later topped by Scott Cummings in 2000 with 14.1).
In Round 18 of the 1996 AFL season, Sumich kicked six goals in a stirring six-point victory over Essendon, but was reported by umpire Greg Scroop for allegedly striking Damien Hardwick, and was suspended for two matches.
[8] Sumich had been playing on-and-off for South Fremantle since he was recruited by West Coast, mainly when recovering from injury or out of form, but returned to the club full-time in 1998, serving as co-captain with Peter Worsfold.