Sumich was selected by the West Coast Eagles with a pre-draft selection before the 1988 National Draft. He made his debut for the club in round one of the 1989 VFL season against , recording 10 disposals. After kicking one goal in the first three games, Sumich was dropped back to South Fremantle, but returned in round seven, and played each of the remaining games for West Coast. He finished with 45 goals for the season to be the club's leading goalkicker, which included four hauls of more than five goals. Against in round 12 he kicked eight goals, setting a record for the most goals kicked in a match by a West Coast player.