Ecclestone played 692 career NHL games, scoring 126 goals and 233 assists for 359 points. He was picked 9th overall by the New York Rangers in the 1964 NHL Amateur Draft and later joined their farm team Kitchener Rangers in the Ontario Hockey Association. The Rangers traded him to the St. Louis Blues in 1967. He played four solid seasons with the expansion team. However, management was unhappy with his involvement in the affairs of the NHL Players Association and traded him, along with Red Berenson, to the Detroit Red Wings in 1971.