Perhaps Cooper might have joined the NHL's Hamilton Tigers like the Green brothers, but in 1924-25 a new team had entered the NHL. The Boston Bruins needed players so Cooper accepted a generous contract and started his NHL career in Beantown.
A bad charley horse made sure his first season was not impressive, but his second season certainly was, scoring 28 goals (2nd most in the whole league) in 36 games, establishing him as one of the NHL's best right wings. He played alongside "Sailor" Herberts. The two were dynamically noted for the speed and perplexing passing plays, catching many defenses off guard.
The following season Cooper got off to a slow start (4 goals in 10 games) and was traded to the Montreal Canadiens in exchange for Billy Boucher. In 12 games with the Habs Cooper fired home 9 goals.
He was sold to the Detroit Cougars just before the 1927-28 season and became a solid though not spectacular scoring threat. In 5 years with Detroit he never missed a game and regularly challenged the 20 goal mark.
Always overshadowed by stars like Howie Morenz, Nels Stewart, Aurel Joliat or Bill Cook, Cooper didn't always get the credit he deserved. When the NHL let up on passing restrictions, Cooper decided to instead of star, set up goals for others. He had 18 goals and 18 assists and because of his unselfish work, George Hay had 18 goals, a figure he might never have achieved without Cooper's help. Hay was in the twilight of his career and it took an unselfish forward like Cooper to give Hay or Herbie Lewis the scoring chances they needed. Lewis scored 20 goals that season.
Cooper scored 14 goals and had 14 assists the next season, 1930-31, and was now slowing down a bit. He exited the NHL in 1932, only to stay in Detroit to play and coach with the IHL's Detroit Olympics for a couple of seasons. He later returned to now-renamed Red Wings and was a long time scout. His most famous find - Gordie Howe. He also is credited with finding Red Kelly, Ted Lindsay, Terry Sawchuk, Harry Lumley and Alex Delvecchio.
He was born in 1899 and died July 4th, 1955 of an apparent heart attack.