McIlvaine played in the Detroit Tigers minor league system for 5 seasons.
During the 1970s, he was a scout in the Baltimore Orioles, California Angels and Milwaukee Brewers organizations.
He became the New York Mets scouting director in 1981 and held that position until 1985.
He was a special assistant to the general manager of the Seattle Mariners.
McIlvaine has returned to the Orioles as senior advisor, player personnel, the team announced Friday, February 12, 2016.