MLB's Expanded Playoffs Have Made October Upsets the Norm

With 12 teams, short series and no reseeding, the 2026 postseason that opens Sept. 29 gives underdogs a genuine path in nearly every matchup.

The 2026 MLB postseason begins Sept. 29, and the expanded 12-team format has made it harder than ever for regular-season dominance to carry into October. Recent years have supplied repeated proof, from the 111-win Dodgers going out early in 2022 to three separate 100-win teams losing their opening series in 2023. In 2025, Milwaukee owned baseball's best record and was still swept by the Dodgers in the NLCS.

The structure itself contributes. Division winners are guaranteed the top seeds even when a wild-card club has a better record, and MLB does not reseed after the first round, which often leaves one side of the bracket far stronger than the other. Short series compound the problem, since a best-of-three or best-of-five gives randomness little time to even out over a sport already shaped by single pitches and small breaks.

The American League offers a live example this year. Tampa Bay is locked into the No. 1 seed, while Texas and Houston are fighting for the AL West with the Rangers sitting at 78-78. A division title below .500 would still come with the No. 3 seed and home field in the wild-card round, potentially producing the worst full-season record ever for a playoff team, below the 82-80 mark of the 2005 Padres.

Home-field edge has offered little protection. In 2022, third-seeded St. Louis was swept at home by Philadelphia and fourth-seeded Toronto lost at home to Seattle, and in 2023 Milwaukee fell at home to Arizona, which went on to reach the World Series. The format has also rewarded slow starters: the 2022 Phillies opened 21-29 and still made the World Series.

The format's future is unsettled. It is part of labor talks between MLB and the players' association, with the current collective bargaining agreement expiring in December and a management lockout expected.