Anything Can Happen in October Baseball
Anything Can Happen in October Baseball
Throw out the regular season. Once the post-season hits, it's a whole new ballgame.
The calendar has turned to October, leaves have begun to fall, and the political ads are going at full strength. That can only mean one thing…playoff baseball is upon us! Thirty major league teams have grinded through 162 games to determine which twelve should have the opportunity to play for baseball’s crown jewel - a World Series ring. Over the course of that six-plus month season, some teams rise a cut above above the rest, while others sneak their way into the playoffs. In the end, however, it doesn’t matter how you get there, because once October baseball begins, everyone’s record ultimately goes to 0-0. What matters is what you do once you get there, and some teams have been better than others.
Baseball is a highly unpredictable sport with great parity relative to other sports. These characteristics become glaringly apparent during the post-season. In fact, since the wild card was established in 1995, a team’s regular season performance (as measured by Baseball Reference SRS rating) has a mere 0.16 correlation with post-season performance.1 This translates to just 2.7% of the variation in post-season success being presumably explained by season-long performance. I measured post-season performance numerically by the below scale, with advancing to each state of the post-season earning the corresponding point, with a win in each round earning a fraction of a point (the value of which is based upon how many wins it takes to advance to the next round).
For example, a team that wins the World Series would get 5 points, a team that advances to the NLCS and does not win a game gets 3.0 points, and a team that gets to the ALDS and wins 1 game would wind up with 2.33 points.
Best Post-Season Franchises
Some franchises have performed better than others in the post season. The table below ranks MLB clubs by post-season success, dating back to the establishment of the league championship series in 1969.2 The table shows the total sum of post-season points by each franchise since 1969, along with their average points when they make it to the playoffs, and average per year of existence (with 1969 being the start).3
Are you at all shocked that the team with the most World Series wins (7) since 1969 leads the pack? The top of this list is fairly unsurprising. However the Houston Astros, who have endured some rough stretches (to the tune of three playoff appearances between 1962 and 1996), and Oakland A’s, whose dumpster fire of team management had put a pitiful product on the field for upwards of a decade-plus, both falling in the top-ten stuck out to me. The A’s did though have an incredible stretch in the 70’s and 80’s. The mustachioed, “Billy-Ball”-playing Oakland squads headlined by Hall of Famers Rollie Fingers, Reggie Jackson, Catfish Hunter, and Rickie Henderson won 4 World Series titles in 5 appearances between 1970-1989.
The scatterplot below compares all-time cumulative post-season success against success per playoff appearance.
As we can see, while the Yankees have ultimately seen the most total success, their per-appearance success lags expectations. The Royals, Phillies, and Tigers ,on the other hand, have not had a whole lot of cumulative success - presumably due to fewer appearances in the playoffs - but tend to do very well when they do play in October.
Cinderella Squads
So far, we have examined the post-season performance of franchises as a whole. But which specific teams have had the most unsuspecting runs in October? For this, I looked at just the Wild Card Era (1995-present), and calculated the probability a team would advance as far as they did in the playoffs given their SRS rating that season, relative to the other teams in the playoffs.
The 2006 St. Louis Cardinals were the least likely World Series winners since the 1995 season. Their 83-78 record and below-league-average -0.4 SRS gave them just a 0.9% chance to win the championship that year given the other teams in the post-season. They were the only team with a negative SRS to win the World Series in that time span. What do SRS ratings and World Series probabilities look like for this year’s post-season participants?
A World Series championship by the Tigers, Astros, Mets, or Guardians would be the most improbable of the Wild Card Era. Will we witness history, or will the heavily favored Dodgers emerge victorious? It’s baseball folks, anything can happen…
Excluding the COVID-shortened and playoff-expanded 2020 season.
Prior to 1969, the best team in each the AL and NL advanced straight to the World Series.
To adjust for the fact that some teams, like the Rays and Diamondbacks, have been around only since the mid-1990s.