The 20 worst MLB single-season teams of all time

Perhaps the basis for this list, the 2023 Oakland Athletics appeared to have the makings of one of the worst teams in baseball history. Now, we'll have to see if that, in fact, is to be the case considering the A's were riding a seven-game winning streak in June. And, as of June 13, they didn't even have the worst record in baseball. That said, Oakland's 10-40 start was the worst through 50 games since the 1932 Boston Red Sox (more about them later), and its 46 losses entering June were the most in major-league baseball history. Needless to say, the potential for historic futility with this group is worth watching.

In 1997, the Marlins rode a high-caliber lineup and strong pitching staff to the franchise's first World Series in the fifth year of its existence. The next season, as result of a massive, and expected, fire sale of major talent like Kevin Brown, Al Leiter, Moises Alou and Devon White — just to name a few — the Marlins posted the worst record in club history. They opened the '98 campaign with an 11-6 home win over the Chicago Cubs, then lost the next 11 in a row. The Marlins also dropped 11 straight spanning May and June, and became the first defending World Series winner to finish last in their division and lose 100 games. The 1998 Marlins season is also memorable for Mike Piazza's five-game stay with the club.

Three seasons removed from a World Series title, won in just the fourth year of the franchise's existence, the Diamondbacks endured what remains the worst campaign in club history. Arizona was expected to contend in a rather sub-par AL West in 2004, but it totaled a major-league low 615 runs and tied for the fewest home runs (135). Now, Randy Johnson did throw a perfect game in May of that season, and won 16, but the staff posted a rough 4.98 ERA. From June 18-July 25, the Diamondbacks went 4-30. They also lost 15 of their final 16 road contests.

From 1938-42, the Phillies lost at least 100 games in each of those five seasons. This '41 team suffered the most defeats among those Phillies groups during the stretch. They started the season 1-6, and didn't post their 10th victory until May 20. The Phillies finished a whopping 57 games behind the first-place Brooklyn Dodgers in the National League. However, Philadelphia did beat the Dodgers on July 1 in the first Major League Baseball game to be televised on a commercial television station (New York's WNBT, which became WNBC).

The present-day Baltimore Orioles endured some lean seasons in recent years, but the franchise's struggles really began from the beginning, back when the club was first based in Milwaukee in 1901. One of the worst seasons in club history, and all of Major League Baseball, came in 1939. The Browns would win their first pennant in 1944, but hardly looked like a winner at the end of the 1930s. This particular group was a terrible team at home, going 18-59 (good for a modern-era low .234 home winning percentage). That loss total was also modern-era major-league record until it was equaled in 2019. 

Amid the annals for one of the most storied franchises in Major League Baseball, the 1932 Red Sox hold a prominent place within that legacy. Of course, for plenty of the wrong reasons. The '32 Red Sox, managed by the forgettable Shano Collins, Marty McManus, and paced by the likes of sweet-swinging Dale Alexander, still hold the major-league record for worst modern-era run differential (minus-349). Meanwhile, the Red Sox's .279 winning percentage is still the worst among any team the franchise has fielded. The good news, it would only be 14 more years until Boston won a pennant. 

We noted that five-year stretch of futility for the Phillies (1938-'42). The '41 team lost the most games during that span, but this '42 club posted the worst winning percentage during that extended rut. These Phillies batted just .232 and slugged only 44 home runs over a 151-game season. They also featured four pitchers to lose at least 16 games. Philadelphia endured a 13-game losing streak from Aug. 26-Sept. 7. Now, for as bad as this team was, and the franchise played while losing at least 89 games each season from 1933-'47, it won the NL pennant in 1950.

The early years of the Washington Senators, which began play in 1901, were rather rocky. The franchise didn't post a winning record until 1912, and managed a World Series title in 1924. However, from 1904-'09, the Senators endured three seasons with at least 102 losses. In '09, Washington suffered the second-most losses in the history of the franchise, which is currently the Minnesota Twins. It's perhaps best known for recording one of the worst months of baseball in the history of the game while losing an historically-high 29 times in 35 contests during July.

The first of two dismal Philadelphia Athletics teams that we will highlight. In terms of modern-era Major League Baseball, the 1919 A's own the fifth-worst winning percentage of all time. As legend goes, Connie Mack appeared to be manager in title only. In actuality, he was a co-owner who helped get rid of some of the franchise's top players during that period. As is the case with some other teams on this list, poor and/or selfish ownership decisions played major roles in why some of these teams endured truly disappointing campaigns. That appeared to be the case with the '19 Athletics, who averaged just 3.3 runs and were shut out 21 times.

As noted, this list has mostly highlighted teams from baseball's modern era. However, there is room for exception when it comes those bad teams from the 1800s. The Louisville Colonels are one of three teams prior to 1901 to finish a season with a winning percentage worse than .200. According to STATS Perform, these Colonels never won more than three straight contests, and endured a 26-game losing streak from May 22-June 22. However, Louisville did manage to sweep a two-game set from the Kansas City Cowboys in July.

Staying in the 1800s, the second-worst winning percentage of that time period belongs to the 1890 Pittsburgh Alleghenys, better known today as the Pittsburgh Pirates. Offense, apparently, was not a strong suit for this club, which hit just 20 home runs and posted a rough minus-633 run differential, according to STATS Perform. The Alleghenys lost 23 in a row spanning August and September, and went a harsh 9-88 on the road during this dismal season that time has long forgot — and rightfully so.

A World Series title would warm the hearts of Pirates' fans to open the 1960s, but the early-to-mid 1950s were not good for the franchise. The '52 season began a string of three straight with at least 101 losses. It seemed destined to fail as the relationship between aging general manager Branch Rickey and star Ralph Kiner had soured, and 13 rookies made the Opening Day roster. The Pirates started 5-28, including 2-13 at home and failed to win back-to-back games over their final 43 contests. Kiner hit just .244, and the team batted .231, while posting a hefty 4.65 team ERA.

Back to the Senators. Yes, the aforementioned 1909 club was bad, but there was actually one installment of the franchise that was worse. This '04 club still holds the franchise record for single-season defeats, and its paltry .252 winning percentage is the fourth-worst in the modern era of Major League Baseball. The Senators opened the season 0-13, with a tie, before winning their first game on May 5. They also won just 15 games on the road, and were either held to one run or shut out a rather amazing 49 times. 

It's important to note that the 2019 Tigers are not the worst club in franchise history. But we'll get to that. Interestingly enough, the '19 campaign got off to a strong start, as the Tigers opened 7-3 and were 12-10 on April 23. However, the bottom dropped out from there. Remarkably, Detroit posted only three more winning stretches of two or more consecutive games, and no more than three in a row, the rest of the way. After going 13-15 on the road in March, April and May, the Tigers won just 12 times away from home for the remainder of the season. They also matched the aforementioned St. Louis Browns with 59 home losses.

The 2018 season kicked off a stretch of three full seasons with at least 108 losses for the Baltimore franchise. Now, the Orioles have mightily turned things around, with the 83-win season of 2021 and continued success in 2022. However, back in '18, this was one terrible ballclub, which failed to rebound from the franchise's first losing season since 2011 from the year prior. Buck Showalter's Orioles finished a historically bad 61 games behind AL East-winning Boston, which also won the World Series. Baltimore started 3-17 on the road, and eventually traded away stars Manny Machado and Zack Britton. Meanwhile, Chris Davis, in the third of a seven-year, $161 million deal, batted just .168 with 192 strikeouts.

The '35 Boston Braves sit tied for fourth, with the aforementioned 2018 Orioles, for most losses in a season within the modern era. It's still quite impressive to think that that loss total, as dubious as it is, remains prominently etched in Major League Baseball history. Not even the legendary Babe Ruth could help the Braves from experiencing a massive amount of futility. Ruth, who also served as vice president and assistant manager, appeared in just 28 games, batted .181, could barely run or field, and ended up retiring as a player on June 1 that season.

We promise, this will be the last time we'll highlight a Philadelphia-associated club. In the modern era, the 117 losses by the Athletics from 1916 are the third-most in Major League Baseball history. For nearly a century, this was considered the worst-ever American League team to ever suit up, and that paltry .235 winning percentage remains the lowest by any major-league club since 1901. Under the direction of manager Connie Mack, the A's finished 54 1/2 games behind the AL pennant-winning Boston Red Sox. From June 3-Aug. 8, Philadelphia went a disastrous 4-56.

There is only one team since 1901 that has lost more games than these Tigers. We'll get to that, soon. No AL team has lost this many games in one season. Under the direction of former Tigers great Alan Trammell, the 2003 Detroit club batted just .240 and posted a 5.30 team ERA with a minus-337 run differential. The Tigers started 1-17 that season, and didn't post consecutive victories until a four-game winning streak from May 4-7. They also lost their first 10 road games, and dropped 12 straight away from home at the end of the season.

Regardless of century or era, when it comes to Major League Baseball futility, the 1899 Cleveland Spiders are the faux-gold standard. No team has ever lost more games or posted a worse winning percentage than these Spiders, who were so bad that the franchise folded following this campaign — its 13th overall. The Spiders were outscored 1,252-529, resulting in a major-league worst -723 run differential. However, as the story goes, the Spiders were destined to fail by team owners, the Robinson Family, which owned another club — the St. Louis Perfectos. Prior to the season, ownership sent the Spiders' best players to St. Louis.

Since 1901, no team has lost more games in a single season than the 1962 Mets. Putting it all into context, this was the franchise's inaugural season. With the legendary Casey Stengel at the helm, the Mets opened their initial campaign with nine straight losses, and also dropped 17 consecutive spanning May and June. That was one of three double-digit losing streaks suffered by New York, which ranked last in the majors in hits (1,318), batting average (.240) and ERA (5.04). Now, the silver lining to this dismal debut for the Mets, and their fledgling fan base, was that just seven years later they were World Series champions.