<P> The Division Series was implemented in 1981 as a one - off tournament because of a midseason strike, with the first place teams before the strike taking on the teams in first place after the strike . In 1994, it was returned permanently when Major League Baseball (MLB) restructured each league into three divisions, but with a different format than in 1981 . In 1981, a split - season format forced the first ever divisional playoff series, in which the New York Yankees won the Eastern Division series over the Milwaukee Brewers (who were in the American League until 1998) in five games while in the Western Division, the Oakland Athletics swept the Kansas City Royals (the only team with an overall losing record to ever make the postseason). Including the 2018 postseason, the Yankees have played in the most division series, with twenty appearances . In 2015, the Toronto Blue Jays and Houston Astros were the final American League teams to make their first appearances in the ALDS . The Astros had been in the National League through 2012, and had played in the National League Division Series (NLDS) seven times . </P> <P> From 1998 to 2011, the wild card team was assigned to play the division winner with the best winning percentage (outside of their own division) in one series, and the other two division winners met in the other series . However, if the wild - card team and the division winner with the best record were from the same division, the wild - card team played the division winner with the second - best record, and the remaining two division leaders played each other . </P> <P> Beginning with the 2012 season, the wild card team that advances to the Division Series was to face the number 1 seed, regardless of whether or not they are in the same division . The two series winners move on to the best - of - seven ALCS . Home field advantage goes to the team with the better regular season record (or head - to - head record if there is a tie between two or more teams), except for the wild card team, which never receives the home field advantage . </P> <P> Beginning in 2003, MLB has implemented a new rule to give the team from the league that wins the All - Star Game with the best regular season record a slightly greater advantage . In order to spread out the Division Series games for broadcast purposes, the two ALDS series follow one of two off - day schedules . Starting in 2007, after consulting the MLBPA, MLB has decided to allow the team with the best record in the league that wins the All - Star Game to choose whether to use the seven - day schedule (1 - 2 - off - 3 - 4 - off - 5) or the eight - day schedule (1 - off - 2 - off - 3 - 4 - off - 5). The team only gets to choose the schedule; the opponent is still determined by win - loss records . </P>

Who has home field advantage in the alds