Internationally Pleau played for the American national team at the 1968 Winter Olympics and the 1969 World Championship.

After being selected off waivers by the Toronto Maple Leafs in the summer of 1972, he instead choose to sign a contract with his hometown New England Whalers of the upstart World Hockey Association (WHA).

Pleau kept his job as general manager, but had to give most of his powers over hockey operations to John Davidson.

Pleau stepped down as general manager of the St Louis Blues on July 1, 2010, with Doug Armstrong taking his place.

Pleau was then named senior advisor to hockey operations, and vice president, with the Blues after 13 years as the club's general manager, the longest tenure in franchise history.