How Have Playoff Teams with Fewer than 90 Wins Fared?

It turns out that the 2023 American League Central division did not end up as the worst-performing division in baseball history. The Twins, Tigers, Guardians, White Sox, and Royals went 358-452, good for a .442 combined winning percentage. That mark eked just past the 2018 AL Central’s combined .436 to avoid such an indignity.

Meanwhile, the 2023 American League East, with all but the Red Sox posting a winning record, set a new high-water mark for division competence, with a combined .554 winning percentage and just surpassing last season’s .541.

The Twins won the Central by 9 games with an 87-75 final record that is just 10th-best among the 12 playoff qualifying teams. Only Arizona and Miami, both 84-win wild card entrants in the National League, are worse.

FanGraphs’ post-season models, as of this writing before the games begin, give the Twins the 11th-best chances of winning the World Series.

So, does a ~2% chance from the experts mean we’re just wasting our time for the next few days? Two percent might as well be zero percent, right? After all, what’s the point of getting our hopes up for a mediocre team, from a franchise that hasn’t won even so much as a single playoff game since 2004?

The data and post-season results suggest that sentiment is far too pessimistic. Teams that have won fewer than 90 games in the regular season have fared better in October than you might think.

The Data

Using Baseball Reference, I went out and gathered data for each playoff qualifying team that won fewer than 90 games in a full, regular season since Major League Baseball implemented the 162-game schedule for the 1961 season. I excluded seasons shortened by pandemics and labor stoppages (2020, 1995, 1994, 1981, 1972).

In total, there have been 46 playoff qualifiers that won fewer than 90 regular season games, including the Twins in 2017, 2009, and 1987. You can find all the data in the table at the end of the post. The 46 post-season qualifiers in my dataset averaged 87.3 wins and 74.6 losses in the regular season and the large majority of them (36) have come since the introduction of the wild card berth in 1995.

Playoff Formats Through the Years

Let’s take a quick detour through MLB’s history of postseason formats. Prior to 1969, there was no playoff bracket, there was just the World Series pitting the American League and National League teams with the best records against one another. From 1969 through 1993, there was a League Championship Series (LCS) in each league to precede the World Series, and four teams qualified for the postseason. The LCS was a best-of-five series until 1985 when it was expanded to the best-of-seven still in place today.

Realignment to create Central Divisions led to the creation of the Wild Card berth and expanded post-season participation to eight teams in 1995. That necessitated a best-of-five Divisional Series round.

A new collective bargaining agreement before 2012 added a second Wild Card berth to each league, increasing the total participants to ten teams. This brought about a new, one-game, Wild Card round before the Division Series, which was in place through 2021. And finally, the playoffs were expanded to twelve teams – three division winners and three wild cards in each league – in 2022, giving us the format we have now.

The Results

Once in the playoffs, whatever the format, teams that have won fewer than 90 regular season games have arguably performed better than you might expect. First and foremost, In total, the 46 underdog playoff contenders have posted a 159-167 combined playoff record (.488 winning percentage). A little more than half (25, by my count) of these teams were bounced in their first playoff series. The flip side of that is that just under half advanced at least one round despite nearly always not being the favorite.

Of course, that overall winning percentage mark is bolstered by the subset of teams that managed to make deep October runs, like the five below who won the World Series:

• 2021 Atlanta Braves (88 wins)
• 2014 San Francisco Giants (88 wins)
• 2006 St. Louis Cardinals (83 wins)
• 2000 New York Yankees (87 wins)
• 1987 Minnesota Twins (85 wins)

Contrast that rate of sub-90 win playoff teams hoisting the Commissioner’s “piece of metal” (nearly 11% of seasons), with how often the team with the best regular season record wins it all. From the implementation of four divisions in 1969 to the beginning of the Wild Card era (25 seasons) eight teams had the best regular season record and won the World Series. That meant in about 32% of those seasons the best team came out on top in October.

Since 1995, now 27 full seasons, that’s happened just 6 times, or in only 22.2% of seasons since the introduction of the Wild Card. Four of the World Series-winning underdog teams above have come since 1995, meaning that a sub-90-win club has won it all in 14.8% of seasons. It’s intuitive that as the MLB playoffs have expanded, the road would have gotten more difficult for the favorites, and we see that play out in the data.

Photo by Daniel Shirey/MLB Photos via Getty Images

Baseball Is More Random Than Other Sports

Compared to other major professional sports, baseball is simply more random in small samples. Studies have shown that it takes about 12 NBA games, and 11 NFL games, for the predictive signal in a team’s winning percentage to be more meaningful than random variation. In baseball, it takes 67 games. Said differently, those are the number of games necessary in each sport to regress a team’s record halfway to the mean — meaning, we’d know half of the observed outcomes were due to talent (while the other half results from randomness).

Another study has demonstrated that in the NBA playoffs, the better team advances about 80% of the time in a 7-game series. No NBA 7th or 8th seed has ever won the title. Only two 8th-seeds have ever even advanced past the second round.

For baseball to achieve a similar rate of the best team advancing from a series, it would need its series to be 75 games, by far the most of any major professional sport. Baseball’s wild card teams advance to the League Championship Series and World Series comparatively frequently.

Over the grueling course of 162 regular season games, there’s more than enough opportunity for the best teams to rise to the top. But in a 3, 5, or 7-game series? We’re mostly just talking about randomness.

October is Different

Compared to other professional sports, baseball is built for playoff upsets and Cinderella runs.

It doesn’t always feel that way as a fan, though. Certainly, during this 0-18 playoff streak for Minnesota, teams like the Yankees have felt inevitable.

But they weren’t, in reality.

This season, Atlanta, with 104 wins, feels like an invincible juggernaut. Same for the Dodgers, now coming off their fourth 100+ win full season in a row.

But they aren’t, really.

Go back above and look at the table of World Series chances again. Atlanta’s are only about 1-in-4. The Dodgers’ are about 1-in-7. It’s much more likely that neither of them will win the World Series than it is that one of them will.

In other sports, it’s not uncommon for the favored team to have ~70-30% or even ~80-20% chances of winning a series. In baseball, the chances are rarely wider than 60%-40% and often are even narrower. This season, FanGraphs projects each of the Wild Card series between ~50-50% (Milwaukee-Arizona) and ~60-40% (Philadelphia-Miami). They are favoring the Blue Jays over the Twins, 55-45. That’s just a touch better than a coin flip.

Does any of this mean the Twins will make a run (or even win a playoff game)? Not necessarily. But it’s not as unlikely as popular narratives might have us believe. And, we shouldn’t be surprised when they do.

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