Plett was a member of the Tulsa Oilers' Adams Cup championship team in 1975–76 and won the Calder Memorial Trophy in 1977 as the NHL's top rookie.

Plett was born into a Russian Mennonite family who had lived in the Soviet Union and then Germany and fled to South America to escape the Second World War.

[1] He played three years in the St. Catharines Black Hawks system, but left the team midway through the 1974–75 Ontario Major Junior Hockey League season following a dispute with coach Hap Emms, joining the tier II Niagara Falls Flyers.

[4] He scored 30 goals in 73 games, added 163 penalty minutes, and helped the Oilers win the Adams Cup as CHL champions.

[4] Playing on the Flames' top line alongside Kent Nilsson and Guy Chouinard,[2] Plett enjoyed his greatest season statistically, setting career highs with 38 goals, 68 points and 239 penalty minutes.

[5] His offensive production fell to 21 goals in 1981–82, a season in which Plett became an outspoken critic of head coach Al MacNeil.

[7] The NHL suspended Plett for eight games early in his first season with the North Stars after he was given a match penalty for slashing Detroit Red Wings goaltender Greg Stefan in the head.

He appeared in 17 playoff games, scoring six points, as the Bruins reached the 1988 Stanley Cup Finals before losing to the Edmonton Oilers.