The MLB playoff field has never been as large as in 2020, but everyone else needn’t have bothered: Like in the old days, when the best regular-season teams in each league automatically advanced to the World Series, the top-seeded Rays and Dodgers clinched the AL and NL pennants, respectively, with Game 7 wins over the weekend.
Thus, the two top seeds will meet in the World Series for only the second time this century, joining the 2013 matchup between the Red Sox and Cardinals. I’ve criticized expanded playoffs for their potential for chaos and devaluing of great teams, arguing—among other reasons—that the best clubs would no longer be as likely to advance as far. This first dabble with a 16-team bracket would seem to dampen any such concerns.
But a sample size of one is not actually sufficient to disprove that possibility, and in fact, analyzing just how unlikely this Rays-Dodgers matchup is provides cause for even more appreciation of both teams’ feats in navigating the tricky playoff field.
According to FanGraphs’ odds before the playoffs began, the Dodgers were the favorite to reach the World Series this year—but only with a 29.1 percent chance. The Rays, meanwhile, were down at 13.8 percent because the projection system thought they were no better than potential opponents like the Yankees and Twins. Multiply those two percentages together, and FanGraphs gave this particular World Series matchup just a 4 percent chance of occuring.
Maybe that figure seems too low, underrating the Rays in particular. But the Dodgers were an abnormally strong no. 1 seed, with a regular-season winning percentage that would translate to 116 wins over 162 games. What would the odds look like if typical no. 1 seeds were forced to compete in a 16-team playoff field, with the same setup as this season?
To approximate an answer, I built a simple predictive model using Bill James’s Log5 method and the average win totals for teams seeded 1-8 in each league from 1998 through 2019. (The first season in that range was the first with 30 MLB teams; on the other end, stopping at 2019 prevents the shortened 2020 season from messing with the data.) This tool is intentionally simple and thus doesn’t consider every factor that influences playoff success; it doesn’t account for injuries or home-field advantage—not particularly relevant for 2020 anyway—or how divisional rank can affect seeding, as with the 2020 Padres, who were seeded fourth despite owning the NL’s second-best record. But as a summary of expectations, it does the trick.
And it shows, in line with the team-specific 2020 predictions, that we would only rarely expect to see both no. 1 seeds reach the World Series. That chance comes out to 6.5 percent for standard no. 1 seeds in a 16-team bracket—or about one in every 15 postseasons.
A 1-seed vs. 1-seed World Series is the most common individual outcome, but it’s not very common compared to the totality of possibilities.
For comparison, with the 10-team bracket MLB adopted in 2012, the odds of both no. 1 seeds reaching the World Series are about double those with a 16-team bracket. Under that setup, my tool predicts that the top seeds would play each other in the World Series 12.4 percent of the time, or one in eight postseasons. Fittingly, in eight years with a 10-team bracket, the top seeds met exactly once, in 2013.
World Series Matchups With a 10-Team Bracket
This chart shows the change in probability for each seed in reaching the World Series under the 10- versus 16-team setups. Seeds 6, 7, and 8 all jump from 0 percent because they have a chance as long as they can play in October, and that probability has to come from somewhere—in this case, the top seeds in each league, who lose up to 10 percentage points of World Series odds thanks to the extra round.
World Series Odds Based on Bracket Size
So even though they were the two top seeds, the overwhelming likelihood was that either the Rays or Dodgers—or both—would have lost before the World Series. And zooming in on the specifics of their playoff math, rather than the hypothetical math, underscores the difficulty. The two no. 1 seeds had to surmount plenty of obstacles.
Both teams trailed in at least one elimination game: the Rays in Game 5 of the ALDS against the Yankees, the Dodgers in games 5 and 7 of the NLCS against Atlanta. They both ended up surviving a winner-take-all contest by one run, via a late home run.
And the Rays were outhit in both the ALDS and ALCS—by fairly large margins—but survived in the maximum number of games each time. They also became the first club to hold a 3-0 lead in a series, then go to a Game 7, and then win.
Rays in 2020 Playoffs
Meanwhile, the Dodgers cruised in the early rounds but benefitted from injuries to three of the four best starting pitchers for their first two opponents: Corbin Burnes for the Brewers, Dinelson Lamet and Mike Clevinger for the Padres. Clevinger threw one inning in the NLDS before leaving with an aggravated injury; Burnes and Lamet didn’t pitch at all this postseason. The Dodgers likely would have won those series anyway, but the Padres clash especially might have unfolded differently with the opposition at full strength.
The Dodgers also needed to come back from a 3-1 NLCS deficit, culminating in a tense Game 7 that made it so the two no. 1 seeds survived three combined winner-take-all games to be able to face off in the final round. This is a far cry from the first 60-odd years of an MLB postseason, when the odds that both no. 1 seeds would reach the World Series were an even 100 percent.
This World Series should be treasured for its pitting of the two best teams in the majors. If the playoffs remain so inviting beyond 2020, as commissioner Rob Manfred wants, it might be a long time before both no. 1 seeds make it this far in the same year again. All the evidence suggests that this outcome is an anomaly. Sure, it might seem obvious that the best teams would have the best chance to win the pennant. But actually, with so many playoff rounds and so many close games, this possibility isn’t obvious at all.
