<P> Major League Baseball is the oldest of America's major professional sports organizations, with roots dating back to the 1870s . As such, it is steeped in tradition . The final series to determine its champion has been called the "World Series" (originally "World's Championship Series" and then "World's Series") as far back as the National League's contests with the American Association starting at the beginning of the 1880s . </P> <P> In 1903, the two modern Major League Baseball leagues began annual postseason play with a one - round system in which the American League team with the best record faced the National League team with the best record in a best - of - seven series (in 1903, 1919, 1920, and 1921 it was best - of - nine) called the World Series; however, there was no 1904 Series because the National League Champion, the New York Giants, refused to play . This single - tiered approach persisted through 1968, even with the expansions of 1961--1962 that expanded both leagues to 10 teams . </P> <P> In 1969, both leagues expanded to twelve teams, which made it more difficult to compete for a league championship because there were more teams competing for the AL and NL pennants . In addition, a team would play other clubs in its own region of the country more than clubs in the rest of the country, creating an unbalanced schedule that in some years could give a team from one region an advantage in fighting for a single pennant . To remedy this, and imitating the other major sports' long - standing playoff traditions, Major League Baseball split each league into Eastern and Western divisions, creating four divisions overall and no worse than a sixth - place finish for any team in any division until later expansions in 1977 and 1993 . This created a new postseason round, which was dubbed the League Championship Series (LCS), a best - of - five series . In 1985 the LCS was expanded to a best - of - seven series . </P> <P> Under this system, it was possible for one of the best teams in a league to be left out of the postseason if it didn't win its division . Most notably, in 1993, the Atlanta Braves and San Francisco Giants finished with the two best records in the majors, with 104 and 103 wins, respectively . However, since both teams played in the National League West, the Giants missed the postseason by a single game . </P>

How many games in the second round of mlb playoffs