1920–1932: The early years
At its inception in 1920, the NFL had no playoff system or championship game: the champion was the team with the best record during the season as determined by winning percentage, with ties excluded. This sometimes led to very unusual results, as teams played anywhere from six to twenty league games in a season, and not all teams played the same number of games or against league talent.
As a result, in the league's first six seasons, four league titles were disputed and had to be resolved by the league's executive committee. In 1920, the Akron Pros went undefeated, tying three games, but two teams that had won more games (and who had both tied Akron), the Buffalo All-Americans and Decatur Staleys, petitioned the league for a share of the title; both teams' petitions were denied, and Akron was awarded the first (and only) Brunswick-Balke Collender Cup. According to modern tie-breaking rules, Akron and Buffalo would be co-champions. Akron and Buffalo both awarded their team members with gold medallions.
The next was in the 1921 NFL season, between the same All-Americans and Staleys (with the latter now being based in Chicago). Buffalo had insisted that the last matchup between the two was an exhibition game not to be counted toward the standings, however, Chicago owner George Halas and league management insisted the game be counted in its standings (the league, at the time, did not recognize exhibition matches). The result was that although the two teams were effectively tied in the standings, the disputed game, having been played later, was given more weight and thus ended up being considered a de facto championship game. Chicago also had one fewer tie game.
A nearly identical situation recurred in 1924, when Chicago tried the same tactic of a final game against the Cleveland Bulldogs, but the league ruled the opposite and declared the last game "post-season", giving the Bulldogs their third consecutive league title.
The fourth and final disputed title was the 1925 NFL Championship controversy between the Pottsville Maroons and the Chicago Cardinals. The Maroons had been controversially suspended by the league at the end of the 1925 NFL season for an unauthorized game against a non-NFL team, allowing the Cardinals to throw together two fairly easy matches (one against a team consisting partly of high school players, also against league rules) to pass Pottsville in the standings. The league awarded the Cardinals the title, one of only two in the team's history, but the Cardinals declined the offer and the championship was vacated.
Only in 1933, when the Bidwill family (which still owns the Cardinals) bought the team, did the Cardinals reverse their decision and claim the title as their own, a decision that continues to be disputed, with the Bidwills opposing any change in the record and the two current Pennsylvania teams in favor. The league recognized the Bidwills' claim to the title and has taken no other action on the issue, although a self-made championship trophy from the Maroons sits in the . Ironically, it was Pottsville's win in that game against the Notre Dame All-Stars that gave professional football legitimacy over college football.
Part of the controversy over these stems from the criteria the league used to determine its champion. The league used a variation of win percentage as its criterion, in which the number of wins is divided by the sum of wins and losses, and ties were excluded. The league began considering ties in its standings in 1972, counting them as half a win and half a loss, but this was not applied retroactively. Had it been, it would have changed the outcome of four 1920-1931 championships: the Buffalo All-Americans would have tied the Akron Pros for the 1920 title, the Duluth Kelleys would have tied the Cleveland Bulldogs for the 1924 title, the Pottsville Maroons would have won in 1925, and the New York Giants would have won in 1930.
Had win-loss differential (the standard method in baseball) been used, the Decatur Staleys would have won the 1920 title by virtue of being one game ahead of Buffalo, and the 1924 title would have been won by the Frankford Yellow Jackets, who were four games ahead of actual champion Cleveland in the standings by that measure.
At the end of the 1932 season, the Chicago Bears and the Portsmouth Spartans were tied with the best winning percentage at .857, with the Spartans record of 6–1–4 and the Bears record of 6–1–6 taken to be six wins, one loss, while the Green Bay Packers finished 10–3–1.
Had pure win-loss differential or the current (post-1972) system of counting ties as half a win, half a loss been in place in 1932, the Packers' record of 10–3–1 (.750, +7) would have won them a fourth consecutive championship, ahead of the Spartans' 6–1–4 (.727, +5) and the Bears' 6–1–6 (.692, +5).
To determine the champion, the league, reportedly at the behest of George Preston Marshall, voted to hold the first official playoff game in Chicago at Wrigley Field. Because of severe winter conditions before the game, and fear of low turnout, the game was held indoors at Chicago Stadium which forced some temporary rule changes. The game was played on a modified 80-yard dirt field, and Chicago won 9–0, winning the league championship. Since the game counted in the standings, Portsmouth finished third behind Green Bay.
A number of new rule changes were instituted, many inspired by the 1932 indoor championship game: the goal posts were moved forward to the goal line, every play started from between the hash marks, and forward passes could originate from anywhere behind the line of scrimmage (instead of five yards behind).
The playoff game proved so popular that the league reorganized into two divisions for the 1933 season, with the winners advancing to a scheduled championship game.