The older of the Plager brothers played his junior hockey with the Peterborough Petes of the Ontario Hockey League (then named Ontario Hockey Association) before spending 6 seasons in the minor leagues, cementing a reputation of hard-nosed defenseman, a reputation he really gained himself when he fought his brother Bob Plager in a memorable brawl right before Christmas 1960, as his Petes faced Bob's Guelph Royals.
The 1967 NHL Expansion opened many doors for many good minor leaguers who could not crack an NHL team's lineup because of its depth; the Blues acquired Plager from the New York Rangers, who owned his rights, along with Red Berenson. It turned out to be an excellent move for the Blues, as Berenson became the team's first offensive star, while Plager was a pillar on St. Louis' blue line, leading a bright defensive brigade that allowed the smallest number of goals in the league for 1968-69, the second smallest for 1969-70 and the third the next season. He was also an outstanding leader; he became the team's second captain of history in 1970 and he held it longer than any other Blues captain ever (except for Brian Sutter) and the Blues reached the Stanley Cup finals on the three first seasons of his reign as captain.
His brothers Bob and Bill Plager were his teammates with the Blues, the first for 11 seasons, the second for 4.
With his career on the decline, Plager became player-coach of the Kansas City Blues, the Blues' farm club, in 1977. He proved his worth by leading his team to the finals and by being named league's MVP. He retired from active playing the next season when St. Louis offered him the head coach role, in replacement of Leo Boivin. It turned out to be the Blues' worst ever season (1978-79) and Plager was fired the following year. He however came back behind the Blues' bench in 1981, as an assistant-coach, a job he would hold until he deceased from cancer in 1988.
|St. Louis Blues captains|
|Arbour | Berenson | Plager | Gibbs | Sutter | Federko | Meagher | Stevens | Butcher | Hull | Corson | Gretzky | Pronger | MacInnis | Drake | Brewer|