List of worst MLB season records

Listed below are the Major League Baseball teams with the worst season won-lost records, as determined by winning percentage (.300 or less), minimum 120 games played.

The following teams finished the season with a .300 winning percentage or lower.

The 1899 Cleveland Spiders own the worst single-season record of all time (minimum 120 games) and for all eras, finishing at 20–134 (.130 percentage) in the final year of the National League's 12–team era in the 1890s; for comparison, this would project to 21–141 under the current schedule, and Pythagorean expectation based on the Spiders' results and the current 162 game schedule would translate to a record of 25–137.

The Spiders had a fair amount of success in the 1890s, with seven straight winning seasons from 1892 to 1898 and a Temple Cup victory in 1895. Meanwhile, the once four-time American Association champion St. Louis Browns had fallen to 29–102 in 1897 and to 39–111 (including 19–67 on the road) in 1898. But the Spiders ownership, the Robison brothers, bought the Browns in time for the 1899 season, creating a conflict-of-interest situation which was later outlawed. On the eve of the season, they traded almost all of Cleveland's good players to St. Louis for very little in return, with respectable results for St. Louis and disastrous results for Cleveland.

The 1899 Spiders set the major league record for most consecutive losses in a season (24, from July 26 to September 16), and had six losing streaks of 10 games or more. The Spiders lost 40 of their last 41 games, finishing 84 games behind the 1899 National League champion Brooklyn Dodgers and 35 games behind the second-last place Washington Senators. They lost 27 games in September, a record for the most games lost in a month until the 1909 Washington Senators went 5–29 in July. Due to paltry attendances, the Spiders played 112 games on the road, finishing with a road record of 11–101 (the 101 road losses is a record which is unbreakable under the current MLB scheduling rules, which allow a maximum of 81 road games).

The 1899 Browns, renamed the "Perfectos" and staffed with all the best players from the 1898 Spiders (six of the Spiders' eight starting position players and four starting pitchers, including the great Cy Young) would improve by a whopping 44½ games, from 39–111 to 84–67. However, all St. Louis did ultimately was to trade places with Cleveland in the standings. The Browns/Perfectos would be renamed the St. Louis Cardinals in 1900, and are unrelated to the American League St. Louis Browns that adopted the discarded nickname and also appear on this list.

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