Expanded Playoffs Have Not Impacted World Series Matchups
Even with more teams making the postseason now than ever before, the quality of the Fall Classic has remained unchanged.
Way back when, until 1969, the the top team from the regular season in each the American and National Leagues met in the World Series. Then, the League Championship Series was established, creating a playoff round between the winners of the East and West divisions in each league for the right to advance to the Fall Classic. Following the 1994 labor strike, the playoffs expanded to eight teams - four in each league - and the Division Series were created. This held until 2012 when an additional wild card spot was granted to each league and the playoffs expanded to 10 teams. Finally, in 2022 the MLB added another wild card in each league and the postseason permanently expanded to 12 teams. Since then, we have seen several higher seeded teams go down early in the playoffs, particularly after a first round bye. This happened with the Orioles and Phillies this year; the Braves, Dodgers, and Orioles last year, and the Dodgers and Braves in 2022. This has led many to question whether or not expanded playoffs are truly resulting in the best teams going to - and winning - the World Series. Does a first round bye stymie the momentum of top teams? Is having more teams in the playoffs, coupled with the extreme parity and variance in the game of baseball, a recipe for upsets preventing the best teams to not win - or even make - the World Series?
I looked back over the last 36 years of the postseason, which consisted of every playoff expansion since the League Championship Series was established, plus five years of when the playoffs was just the LCS.1 I looked at the combined Wins Above Replacement (WAR) for the teams in the World Series, average winning percentage in the matchup, and average team SRS rating from Baseball Reference.2
What I found was that the quality of the teams meeting in the Fall Classic has remained relatively constant throughout the expansion of the playoffs. The charts below show how the average winning percentage and total WAR in the World Series has been largely consistent over time.
Only in 2019 did we see a combined WAR significantly higher than (2 standard deviations above) the 36-year average. Just 2020 and 1995 had winning percentages significantly higher than the overall average.3 Oddly enough, the year in which we saw the best average winning percentage was in 2020, when the playoffs were actually ultra-expanded to 16 teams due to the COVID-shortened regular season. Naturally, this should come with a slight caveat as the regular season was only 60 games long, so it would be unwise to confidently compare that season to any full 162-game season. Here is a breakdown of the averages for total WAR, average SRS, and average winning percentage for teams that have made or won the World Series over three time-spans:
Since 1988 - the entirety of this time period we have been discussing, dating back to when the playoffs were just the League Championship Series and World Series
Since 1995 - When the Division Series and two additional teams were added in each league.
Since 2012 - When an an additional wild card team was added in each league
*Note - I did not look at 2022 - present, as that sample size is too small to be reliable.
Average winning percentage of teams making the Fall Classic has remained essentially unchanged across playoff expansion. In fact, contrary to the playoff-expansion skeptics, we see teams with better winning percentages, higher WAR, and better SRS ratings winning the World Series under more expanded playoffs.
Here is a similar table examining the average MLB rankings of the teams making and winning the World Series for each of those stats.
Those who argue that expanding the playoffs makes it more difficult for the true best teams to make, and subsequently win, the World Series would expect to see these average rankings rise as the postseason field grows. That’s not obvious here. While we do see a slight rise in the average WAR ranking, average SRS ranking, and average winning percentage ranking for teams making the World Series, the rise is not substantial. Average SRS and average winning percentage rank since 2012 is only 0.5 spots higher than over the full span, with average WAR rank only 0.3 spots higher. In terms of teams winning the World Series, we actually see a very small decrease in average SRS and winning percentage rankings, indicating that, on average, better teams are winning the World Series under expanded playoffs.
Here is a detailed look at the combined rankings for the aforementioned stats in all World Series matchups over the past 36 postseasons.
The Bottom Line
An expanded postseason has not impacted the quality of the World Series, and the best teams are getting to - and winning - the Fall Classic just as often now as they always have. More teams in the playoffs gives more fans reason to stay locked-in later in the season, and makes for some Cinderella postseason runs that add to the excitement of the game. Postseason Baseball is perfect, and always will be.
1988-2024, note, there was no postseason in 1994 due to the labor strike
SRS rating derives from a team’s run differential and strength of schedule from Baseball Reference
Total WAR was significantly below the average in 2014 and 2006. There were no years in which the combined winning percentage was significantly below the 36-year average.
Forgive me, because I know this is going to sound reductive, but if the numbers say that on average the team that made the World Series was the fifth best by Win% before, and it's still fifth place now, wouldn't that mean that randomness prevailed before and still prevails now, and couldn't that be used as an argument against playoff expansion? Fifth place is a long way from the best.
The inventors of the World Series knew what they were doing. By not creating a tournament, and locking out every team that was not good enough to win the league, they allowed as little randomness to seep in as possible. When they went to the LCS in 1969, it allowed some randomness in, but it was by and large okay, but it feels like the eight team playoff destroyed all of that, and everything beyond that has just been adding fuel to the already burning bonfire.
What do you think is the probability of the better team winning a baseball series? 60%? Is that generous? Either way, there's a lot of room for luck to squeak in there, meaning that minimizing the total number of playoff series should be the goal if you're looking to create a meaningful World Series. Of course, baseball is not looking to do that. They're looking strictly to line their pockets, which is why the Super Bowl is now watched by one third of the country, instead of the World Series, which used to be watched by one third of the country.
I think somewhere along the way, baseball lost sight that people don't watch the World Series just because it's the World Series. They want to see great teams battling each other, and does two teams that are the fifth best team in the league on average satisfy that requirement? Evidently not, as the falloff in the popularity of the World Series indicates that people are not buying this. They'll buy a WS like the one that's currently happening, because it's one great team against another, but one like 2014? Nobody cares.
I wish this analysis went a bit further back in time, so I could tell whether I'm looking with rose-tinted glasses back at the LCS era, but I just don't recall the WS so often being conducted between two third place teams back then. It's possible that I'm wrong about this, because the decline of baseball's popularity did begin around the time of the LCS's institution, indicating to me that the general public did not like this expanded playoff idea, so it's possible that it sucked back then too.
The genie is out of the bottle now. We cannot go back to the good old days, so in the modern era I just have to watch the WS that contain great teams (like the current one), and skip the ones that don't (like the last one).
Wow, I've been waiting for this sort of outstanding analysis for literally years. If I am interpreting this correctly, this is a very important insight on several dimensions. First, I want to make sure I understand your analysis here and the meaning of the words "playoff-expansion skeptics" when you say:
"...Average winning percentage of teams making the Fall Classic has remained essentially unchanged across playoff expansion. In fact, contrary to the playoff-expansion skeptics, we see teams with better winning percentages, higher WAR, and better SRS ratings winning the World Series under more expanded playoffs."
Specifically, am I correct to interpret this as saying that the expanded playoff format is essentially meaningless from a World Series results perspective? If so, does that also mean that teams below some minimal high-level performance at season's end (e.g., below say the top two teams in each League) are largely irrelevant to the World Series outcome on average?
If so, this resonates with me. I'm a huge skeptic on the expansion of any playoffs not because of some counterintuitive dilution of the end result from adding teams, rather, that the entire concept of expanding the Playoffs by adding lesser teams to the mix is almost always a waste of time.
What say you?
Presuming you agree with that, the consequences are significant. For one, it contradicts the popular notion in the media that teams in the mix of 12 or near spot 12 should be aggressive buyers at the trade deadline by diluting their farm system talent in exchange for a hope and a prayer of getting to the World Series that rarely happens.
This would suggest that only if you are one of the 4 teams or so with the highest World Series odds and a gap to fill at the deadline should you be buying. Everyone else is just more likely hurting their futures for a futile effort. Again, this strikes me as undeniably true (see 2023 Angels and 2024 Padres as recent examples).
Thanks again for a terrific piece.