The NHL and the World Hockey Association had been discussing a merger, on and off, for more than two years. At the end of the 1978-79 season, only six WHA teams were operating. The NHL agreed to take in four of them, the Edmonton Oilers, Hartford Whalers, Quebec Nordiques, and Winnipeg Jets. With Edmonton's arrival, the Wayne Gretzky decade began.
Gretzky had joined the Oilers as a 17-year-old the previous season and had finished third in WHA scoring. In his first NHL season, he scored 137 points to tie Marcel Dionne for the league leadership, though Dionne was awarded the Ross Trophy because he had 2 more goals. However, Gretzky did win the Hart Trophy as the league's most valuable player.
But the first four years of the decade belonged to the New York Islanders. The Islanders had been building an outstanding team for some time. Over the five-year period from 1974 through 1978, three Islanders won the Calder Trophy as rookie of the year. In 1978 and 1979, the team had suffered embarrassing first-round playoff upsets.
In 1979-80, the Philadelphia Flyers re-emerged as the league's best regular-season team, finishing 25 points ahead of the Islanders in the Patrick Division. The Buffalo Sabres dislodged the Boston Bruins from first place in the Adams Division and finished second to Philadelphia with 110 points. The Montreal Canadiens, winners of the Norris Division again, were third with 107 points, despite the retirement of goalie Ken Dryden and the loss of Coach Scotty Bowman to Buffalo.
But Montreal's hopes for a fifth straight Stanley Cup were wiped out by a quarterfinal loss to the Minnesota North Stars. Buffalo swept Chicago in the quarterfinals, but lost to the Islanders in six games in the next round. The Islanders had already eliminated Los Angeles and Boston.
In the Stanley Cup finals, they were underdogs to the Flyers, who had won 11 of 13 playoff games to get to this point. But the Islanders took home-ice advantage away from Philadelphia when Denis Potvin scored in overtime to win the first game. The next four games were all blowouts for the home team.
In Game 6, at New York, the Islanders held a 4-2 lead at the end of two periods, but the Flyers tied the score to force overtime. At the 7:11 mark of the extra period, Islander Bob Nystrom redirected a centering pass from John Tonelli into the net to win the game and the Stanley Cup.
Bryan Trottier, who scored a record 29 post-season points, won the Conn Smythe Trophy as the most valuable player of the playoffs.