During this time, the WIFU's relationship with the CRU remained strained. Teams in the Western league continued to push for rule changes intended in part to make the game more attractive to U.S. players familiar with the American game. This came to a head in 1940 when the CRU again barred the Western champion Blue Bombers from the Grey Cup on the grounds that the West had played using rules that differed from those in the East. However, the most important pre-war development, implemented in both East and West on a permanent basis for the 1936 season, was the introduction of automatic divisional playoffs. Prior to the formation of the WIFU, the playoff format in Western Canadian football was similar to the format used in U.S. professional leagues right up to the introduction of the Super Bowl in that playoff qualification was limited to union winners and intra-provincial playoffs were only used (when necessary) to break ties in the standings. However, the founders of the WIFU had come to recognize the popularity of the Western playoffs as well as the need to ensure as many regular season games as possible were meaningful so as to encourage fans to attend games, and therefore decided that a multi-team playoff was necessary for the league to remain solvent. The playoffs consisted of the top two teams until Edmonton joined the league in 1938, when they were expanded to three teams, reverting again to two teams after Edmonton dropped out of the WIFU.