Postseason “Magic”: Reality or Myth?

by Deb Seymour

Every year, across the world of competitive sports, there’s a team that seems to defy all logic by winning the championship in their respective sport. As most serious sports fans know, there’s no easy way to explain the magic some teams suddenly discover in the playoffs; and yet, somehow, there’s definitely “a there, there.” If I told you, however, that I had an easy answer to the title question of this blog post, I’d be lying to you.

And yet, every postseason, there are the teams that seem to bring the magic and have all the luck go their way and benefit from the least negative refereeing and, in short, outplay what their entire regular season looked like. It’s enough of a phenomenon to be regularly discussed by both everyday fans and sports pundits alike. It has the feel of being both “clutch” and “hot” rolled into one. It can lead to sudden game swings and long postseason winning streaks that are talked about for years.

As a fan, it’s simultaneously exhilarating and maddening to know that it’s not necessarily always the best team that wins the championship; it’s the team that somehow “brings the playoff magic.” So what is “the playoff magic?”

When I first became a serious sports fan, I just assumed that one of my teams, who’d had a pretty great regular season, would be a superstar team in the postseason. And one of my friends, who’d been a non-casual sports fan for far longer than I, said to me “it doesn’t work that way — you’ll see. It’s whoever’s hot that’s going to win.” In a more recent conversation, with a friend who’s a baseball coach, what I was told is that “there’s always an element of luck involved.” But the phenomenon must have been studied; and if you read my blog regularly, you know that I like to dig around in the stats and research — and so here’s a little taste of what “postseason magic” research looks like.

Below, what you see is from “Indicators of Postseason Success in Major League Baseball,” which studied what MLB World Series-winning teams do during the regular season that
indicates a higher chance of success in the postseason. The study used a number of algorithms, weighting types of wins in the regular season as indicators of success in the postseason. One of the initial observations the study makes is that the teams with the greatest overall number of wins in the regular season do not win the World Series more often than other teams that make the playoffs. That issue having now been set aside, below I’ve extracted some of the more relevant information.

Source: https://www.stat.berkeley.edu/~aldous/Research/Ugrad/soncrant_presentation.pdf

As it turns out, statistically, being “hot” in September, for the last month of the regular baseball season, does not reliably predict success in the postseason. But here is some information that appears to be more predictive of postseason success, and it’s a start toward debunking the myth of “postseason magic”:

Source: https://www.stat.berkeley.edu/~aldous/Research/Ugrad/soncrant_presentation.pdf

Taking these latter tables into consideration, the resultant conclusions of the study are these: When we take into account that teams have to both (a) make the playoffs, and (b) go on to win the World Series, we find that there is a 47% chance that the World Series winner is a team with a regular season win-percentage against top teams greater than .575. And that is a significant improvement over blindly choosing the “best” regular season team to win it all, where “best” is the team with the best winning record overall. This also presents at least some statistical confirmation for the notion that MLB’s weaker division winners stand less chance of winning a World Series than do Wild Card winners that come out of stronger MLB divisions.

Now, I’ll grant that 47% doesn’t solve any real issues like the “postseason magic — fact or fiction?” dilemma, but it does get us a little closer to at least some predictability about World Series winners over time.

Here’s another stab at discovering what’s a real versus imagined advantage in a postseason championship series. In “Is There a Home Choke in Decisive Playoff Basketball Games?,” the authors begin with this opening:

“There is a common belief in athletics that competing on one’s home field or court provides a distinct advantage over one’s opponent. Athletes, coaches, spectators, and commentators alike frequently advocate the merits of playing at home, due in part to familiar surroundings and a supportive audience. A major reason sporting teams strive to perform well throughout a season is to gain home-field advantage during playoff competition. Athletes regularly comment about the importance of having the home field or court during high-profile contests, such as championship games or the pivotal game of a playoff series.” (Journal of Applied Sport Psychology, 21: 148–162, 2009)

After that kind of introduction, you’d suspect the authors of the article would likely go on to debunk the strongly held belief that home field/court advantage in a pivotal NBA playoff game is actually a real advantage. And yet, after citing much previous conflicting research from hockey, baseball, and other sports, their study goes on to show that in a pivotal game seven in the NBA playoffs, home court advantage stands up in the fourth quarter — unless the home team is almost numerically already out of the game. So there is some substance to the home field advantage idea, it appears.

There are, to be sure, many more facets attached to the concept of “postseason magic” beyond which team won the most games against the toughest teams in the regular season and whether or not home field advantage is a factor in winning decisive playoff games — such as whether momentum once the postseason begins is a real or imagined feature in who ultimately wins the championship. We can all probably agree, though, that some years, in some sports, it just seems to be Team XYZ’s year. And that’s the magic part. Because winning and losing isn’t predictable all the time. It’s one of the reasons the Vegas odds of which team will win it all keep shifting even mid-game, much of the time. But if it were entirely predictable, would we even watch? Whose juices don’t get flowing when the unpredictable seems to be happening? I’ll happily take a little bit of magic stirred into my analytics cocktail. And, as a result, keeping it real doesn’t always mean “may the best team win.”

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