Are the Arizona Diamondbacks the most unlikely team ever to earn a slot in a league championship series?
The D-backs' résumé, for an LCS team, is wild: They won 84 games -- 10 more than they did a season ago and 32 more than in 2021. They were outscored by 15 runs this season. They were below the big-league average in both OPS+ and ERA+.
These are not the traits of a playoff winner and yet, here we are. After shocking sweeps of the Brewers in the wild-card round and the 100-win Dodgers in the division series, we have a National League Championship Series with as close to a Cinderella team as baseball has had in some time.
There is a good chance that with the benefit of hindsight, we'll come to view this late-season Arizona surge as the start of what should be a sustained window of contention. Things could go awry, but with players like Corbin Carroll, Alek Thomas, Jordan Lawlar and Brandon Pfaadt in the early stages of their careers, this isn't likely to be a one-and-done playoff appearance for the Snakes.
So this question of unlikelihood is more about where the Diamondbacks have come from than where they are likely to go. It isn't meant to slam them, but to help us appreciate what they've accomplished so far.
Let's run through the Diamondbacks' dossier one item at a time, put them into LCS historical context and combine it all into a Cinderella Rating, so we can see where Arizona stacks up.
Wins per 162 games
Diamondbacks' total: 84 (tied for 211th of 216 LCS teams)
Counting this season, there have been 216 teams to reach the LCS round since it was established in 1969. We're using the measure of wins per 162 games so that we can prorate the win totals for teams that played fewer games than that during a season. Arizona's 84 wins this season slots it into a three-way tie for 211th, along with the 2008 Dodgers and the 1984 Royals.
The only teams that rank behind Arizona are the 2006 St. Louis Cardinals, who went 83-78 (prorated win total of 83.5), the 1973 New York Mets (82-79) and the 2020 Astros, who went 29-31 for a prorated win total of 78.3. That Cardinals team won the World Series, while the 1973 Mets took the National League pennant and pushed the eventual champion Oakland Athletics to seven games in the World Series.
I also calculated a correlation coefficient between wins per 162 games and the number of LCS games played for each team in a season dating back to 1969. This includes all teams, not just the ones who played in an LCS. Expressed as an integer between 0 and 100, the higher this number is (the closer to 100) the more it suggests the two categories are related -- and this will all be important for our final formula ranking. The correlation coefficient between this category and LCS games played is 48.
Pythagorean wins per 162 games
Diamondbacks' total: 79.5 (214th of 216)
As mentioned, the Diamondbacks were outscored by 15 runs during the 2023 regular season. Convert that differential into an expected winning percentage and apply that to a 162-game standard, and you end up with 79.5 expected wins.
Only two teams during the LCS era have done worse. Those were the 1987 Twins (79.1 Pythagorean wins) and, remarkably, the 2007 Diamondbacks. Those Twins won the 1987 World Series; that Snakes squad lost to the Rockies in the NLCS.
The correlation coefficient between this measure and LCS games played is 47.
Foundation wins
Diamondbacks' total: 126 (216th of 216)
This is really what we mean when we talk about "where" the Diamondbacks came from. For the purpose of this analysis, what we're calling foundation wins is simply the team's total wins per 162 games over the two seasons prior to their LCS appearance. No team has earned an LCS slot with a lower foundation total than the 2023 Diamondbacks.
Others have been close, though, and that includes some of the more remarkable turnaround stories over the last few decades in the majors. The Rays had just 127 foundation wins when Joe Maddon's team zipped to the 2008 World Series, where they lost to the Phillies. Just ahead of them, at 128, are ... the 2023 Texas Rangers, who join this year's Diamondbacks in the rebuilders-made-good class. Others in this group include the 1969 Mets (133.6 foundation wins -- remember, we're prorating to 162 games) and the 1991 worst-to-first Braves (128.4)
The correlation coefficient between this measure and LCS games played is 26.
The Cinderella Index
The three categories we describe give you an adequate story of how unlikely this Arizona run is, but let's combine them into one rating and leave you with a final Cinderella leaderboard. To do this, I calculated an index score for each of the 216 LCS teams since 1969 in each of these three categories, then I came up with a weighted average that is based on our aforementioned correlations.
The Cinderella Index leaders since 1969? Drum roll please ...
1. 2023 Diamondbacks (122.1)
2. 1987 Twins (119)
3. 1984 Royals (116.8)
4. 1973 Mets (115.4)
5. 2007 Diamondbacks (115.3)
6. 2020 Astros (113.9)
7. 1996 Cardinals (113.1)
8. 2003 Cubs (112.5)
9. 2008 Dodgers (112.4)
10. 2014 Royals (112.2)
11. 1982 Braves (111.9)
12. 2022 Phillies (111.6)
13. 1996 Orioles (111.2)
14. 2019 Brewers (111)
15. 2006 Cardinals (110.8)
16. 1990 Red Sox (110.7)
17. 2007 Rockies (110.1)
18. 1995 Mariners (110)
19. 2014 Giants (109.7)
20. 2003 Marlins (109.5)
So there you have it. Through the steps we traced here, we've made a case that this year's Diamondbacks are the most unlikely LCS entrant we've ever seen.
Of course, we have to acknowledge one important change: Arizona was the six-seed in the NL bracket, which means that in many previous seasons, it likely wouldn't have even had a chance to win a division series and make an LCS. Sure, there has been a smattering of teams over the years that ranked sixth or lower in their leagues by winning percentage and advanced to the playoffs either because of an expanded format (2020) or because of imbalances between divisions -- but it was rare.
Until now. Starting in 2022, in the new playoff format, the six-seed was baked in. And in just those two short years, we've seen this year's Diamondbacks, plus the 2022 NL champion Phillies at No. 12, the 2022 Padres at No. 29, the 2023 Rangers at No. 32 and the 2023 Phillies at No. 38.
In other words, Cinderella teams might just be a new reality in the world of a 12-team playoff format. So far, though, no one wears the glass slippers quite so well as this year's Arizona Diamondbacks.