Recruited from Federal League and future VFA club Springvale, Koop, a utility, played 15 games in three seasons from 1979 at South Melbourne.
He spent 1982 to 1984 in the SANFL playing with Woodville and then returned to the VFL at North Melbourne.
[2] It was at Melbourne that he got selected most regularly and despite playing in both of his club’s semi-final wins of 1987 and 1988, he missed each of the preliminary finals.
Koop would remain at Melbourne in 1989, but did not play a senior game, and for 1990 he returned to his former club in the VFA.
Koop coached at the Cranbourne and Frankston YCW clubs, before joining the Officer Kangaroos in 2017.