Though he missed the start of the 1952–53 season due to a separated shoulder, Armstrong earned a permanent spot on the Maple Leafs' roster. He quietly established himself as an important contributor for Toronto by recording 25 points that season, then scoring 32 points the following season and 28 in 1954–55. A 48-point season in 1955–56 was second on the team to Tod Sloan's 66. Armstrong then led the Maple Leafs in scoring with 44 points in 1956–57 despite missing 14 of his team's games. He was named to play in the NHL All-Star Game in both seasons. They were the first two of seven he ultimately played.