He played at center in the National Basketball Association (NBA) for the Seattle SuperSonics, Philadelphia 76ers, Cleveland Cavaliers, and the Milwaukee Bucks.

[2] In 1966, Rule and Colorado State made the NCAA tournament but lost to a Houston team that featured future Hall of Famer Elvin Hayes.

[4] Rule played in the Amateur Athletic Union for the Denver Capitol Federal during the 1966–67 season and was named an All-American.

[5] A second round pick in the 1967 NBA draft, Rule quickly became one of the stars of Seattle's expansion franchise.

[6][7] Named to the 1967–68 NBA All-Rookie Team, Rule's 18.1 points per game average stood as the SuperSonics rookie record for forty seasons, until broken by Kevin Durant in 2008.