Born in Sarnia, Ontario, Butler was selected 55th overall by the New York Rangers in the 1971 NHL Amateur Draft despite scoring only six goals in junior the previous season.
In 1974–75, Butler's first full NHL season, he recorded 17 goals and 16 assists for 33 points in 78 games, and earned a positive reputation for his speed, hustle, and quality defensive play.
In St. Louis, he received the opportunity to play on one of the Blues' top lines with Garry Unger and Bob MacMillan, and responded with the finest year of his career, finishing the 1975–76 season with 17 goals and 41 points despite missing 14 games due to injury.
Although his offensive numbers suffered and he finished the year with just 18 points, he was by now considered one of the best penalty killers in the NHL, and was an important part of a Toronto team which nearly reached the Stanley Cup finals in 1978.
(Dave "Tiger" Williams was also dealt to Vancouver as part of the same trade; in exchange Toronto received Bill Derlago and Rick Vaive.)