A switch hitter who threw left-handed, Fox was taken in the 22nd round (566th overall) of the 1984 Major League Baseball draft by the Toronto Blue Jays. He failed to sign and re-entered the draft. In 1985, the Philadelphia Phillies took him in the 13th round, 330th overall; again, he did not sign. Finally, in the 1986 draft, the Seattle Mariners took him fifth overall in the first round, and he signed with them.