The Boycott of 1904

The 1904 Series was supposed to be between the AL's Boston Pilgrims and the NL's New York Giants. The Giants' owner, John Brush, refused to allow his team to play, citing the inferiority of the upstart American League. Brush also cited the lack of rules under which the games would be played and the money would be split. During the winter of 1904/05, however, Brush proposed what came to be known as the "Brush Rules", under which the series would be played over subsequent years.
One rule was that player shares would come from gate receipts from the first four games only. This was to discourage teams from throwing early games in order to prolong the series and make more money. Receipts for later games were split among the two teams and the National Commission (the new governing body for the sport, which was able to cover much of its annual operating expenses from World Series revenue).
The list evolved over time. In 1925, Brooklyn owner Charles Ebbets convinced owners to adopt the current 2-3-2 system of scheduling World Series games (one team would host the first two games, the other team would host the next three, and the first team would host the last two if necessary; the leagues alternated which representative would host the first games).