Major League Baseball postseason

• 1. Introduction

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  The Major League Baseball postseason is a tournament that has been reinvented more than half a dozen times since its modern form began in 1903. Two teams once played a single championship series to settle everything. Today, twelve teams compete across four rounds over roughly one month. What drove those repeated expansions? And why does the question of who hosts which game still spark arguments more than a century after the first pitch?

  The answers run through players' strikes, pandemic bubbles, All-Star Game embarrassments, and the perpetual tension between rewarding regular-season excellence and keeping more cities in the race deep into October. The structure of the postseason is not just a logistical question. It reflects every era's negotiation between the owners, the players' union, and the fans who fill those seats whose money funds the whole enterprise.

• 2. One Series, Two Teams

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  From 1901 through 1968, winning the pennant meant finishing with the best record in your league. That was it. No second chances. The World Series, which traces its name back to National League contests with the American Association starting in the 1880s, was the only postseason round.

  Modern annual postseason play kicked off in 1903 with a best-of-seven matchup between the American League and National League champions. In 1903, 1919, 1920, and 1921, the format was actually best-of-nine. The very first year set an awkward precedent: there was no 1904 Series because the National League champion New York Giants refused to play.

  This single-round setup survived for more than six decades, even as both leagues expanded in 1961 and 1962 to ten teams apiece. The math of pennant races grew more complicated, but the postseason itself stayed simple. That simplicity held until 1969 brought an expansion to twelve teams per league and made the old model genuinely unworkable.

• 3. Divisions and the First Round

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  When both leagues reached twelve teams in 1969, MLB split each into East and West divisions, four divisions of six teams each. A new round was born: the League Championship Series, in which the East and West division winners played a best-of-five to determine who went to the World Series. In 1985, that series was extended to best-of-seven, which is still the format today.

  The division era exposed a structural flaw almost immediately. Under this setup, a team could post one of the best records in all of baseball and still miss October entirely if it finished second in its own division. The most striking illustration came when the Atlanta Braves and San Francisco Giants finished with 104 and 103 wins respectively, the two best records in MLB that year. Both played in the National League West. The Giants missed the postseason by a single game.

  The 1981 players' strike briefly forced a preview of what a multi-round postseason could look like. Because the strike split the season into two halves, the division winners from each half met in a best-of-five division series before the League Championship Series. That extra round would not return on a permanent basis for more than a decade.

• 4. The Wild Card Arrives

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  In 1994, MLB realigned by adding a Central division to both leagues, which meant an odd number of division winners in each league. To fill out the bracket, a wild card spot was introduced: the team with the best record among division runners-up earned a postseason berth. The format was modeled on the original post-merger NFL system.

  The wild card directly addressed the Giants problem from the earlier era. A team with the second-best record in its league would now qualify for October even if it did not win its division. The field in each league grew from two teams to four, and overall postseason participation doubled from four teams to eight.

  A permanent Division Series became the new first round, a best-of-five. The format was set for the 1994 season, but the players' strike that year wiped out the entire postseason. The new structure finally played out on the field in 1995. Under the rules of that era, the wild card team faced the division champion outside its own division with the stronger record; the other two division winners met in the second Division Series of each league.

• 5. The All-Star Game Decides October

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  The 2002 All-Star Game ended in a tie, and the reaction from fans and sportswriters was sharp. Commissioner Bud Selig felt the criticism personally: the game had been played in Milwaukee, Wisconsin, his home city. To make the midsummer game matter, MLB announced in 2003 that the league whose team won the All-Star Game would earn home-field advantage in that year's World Series.

  For home-field in the World Series itself, the format settled into a 2-3-2 pattern in 1924, a structure designed to reduce travel costs. That pattern, with brief exceptions during World War II when wartime travel restrictions forced a 3-4 format in 1943 and 1945, has persisted. The 1944 Series was an exception to the wartime exception: it was played entirely in one stadium in St. Louis because both participants, the Browns and the Cardinals, were crosstown rivals.

  The All-Star-decides-home-field rule lasted until a new collective bargaining agreement after the 2016 season. Starting in 2017, home-field advantage in the World Series went to the team with the better regular-season record. In nine of eleven recent seasons, home-field advantage has not decided the outcome: between 2014 and 2022, and again since 2023, the home team did not win the deciding game on its own field. The 2022 World Series, won by the Houston Astros in six games at Minute Maid Park, was the first time since 2013 that the home team actually won the decisive game on its own turf.

• 6. Expansion and the Pandemic

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  In November 2011, Commissioner Bud Selig announced that a second wild card team would be added to each league within two years. The change arrived in 2012. The two wild card teams in each league met in a single elimination game, with the winner advancing to face the division winner with the best record in the Division Series. This pushed the postseason to ten teams.

  The COVID-19 pandemic prompted the most dramatic short-term restructuring in the postseason's history. On the 23rd of July 2020, the MLB Players Association and owners agreed to expand to a sixteen-team playoff for that season alone. Eight teams from each league were seeded, and all first-round games were hosted by the higher seeds to reduce travel. The round was called the Wild Card Series and used a best-of-three format. All other series, the Division Series, League Championship Series, and World Series, remained unchanged. The 2020 World Series was played entirely at a neutral site; the Los Angeles Dodgers, designated as the home team, won it, making them technically the first team since 2013 to win a Series as the home side.

  MLB reverted to the ten-team format for the 2021 postseason before the next round of collective bargaining reshaped things again.

• 7. The Twelve-Team Era

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  The 2022 collective bargaining negotiations produced the current format: twelve teams, six per league, consisting of three division winners and three wild card teams. The two division winners with the best records in each league receive byes directly to the Division Series. The third-place division winner and the three wild card teams play a best-of-three Wild Card Round, hosted entirely by the higher seed.

  Tie-breaker game 163 was eliminated under this format. Seedings and playoff spots are now settled through a hierarchy of criteria: head-to-head record, then intra-division record, then inter-division record, then record in the last half of intra-league games, with coin flips or a draw of lots as a final resort for ties involving two or three-plus teams respectively. Brackets remain fixed with no re-seeding after each round.

  The players' bonus pool under this format is funded by sixty percent of the gate receipts from the Wild Card games, the first three games of each Division Series, the first four games of each League Championship Series, and the first four games of the World Series. Capping the pool contributions at the minimum number of games in each series removes any financial incentive to drag out a series. Since 2022, the World Series winner takes thirty-six percent of the total pool, the runner-up twenty-four percent, with smaller shares cascading down to the four Wild Card losers at 0.75 percent each. Individual shares within a team are voted on by the full-season players at a meeting chaired by the union representative, held after the trade deadline on July 31.