He then spent the next 20 years in off-ice positions with the New York Rangers, Minnesota North Stars, and Vancouver Canucks before joining the Edmonton Oilers organization in 1981.

While with the Oilers, Muckler served as an assistant coach with the Stanley Cup winners under head coach/general manager Glen Sather in 1984 and 1985.

Initially the club's director of hockey operations, he soon accepted the team's head coaching position and guided the Sabres for the next four seasons.

Muckler was hired by the Ottawa Senators as general manager in June 2002 by owner Eugene Melnyk and presided over what was arguably the team's most successful period.

Among the trades made in his tenure included Marian Hossa for Dany Heatley and luring 40-year old Dominik Hasek to a one-year deal while letting players such as Zdeno Chara leave in free agency.

The team ultimately reached the Stanley Cup finals in 2007 but lost to the Anaheim Ducks in a five-game series.