Long-time readers might know about my semi-obsession with the idea of a World Series match-up consisting only of expansion teams. It seems like the type of thing that should have happened; after all, for the past eighteen seasons, we’ve had league that’s nearly 50/50 original teams/expansion teams (16/14 to be precise, but that’s pretty close). Despite that, though, expansion teams have been extremely underrepresented in October. The lack of an all-expansion team World Series was just another symptom of that.
And now, that’s over, thanks to the Mets’ sweep of the Cubs (the AL side was assured once the Yankees lost). Like I said a month and a half ago, this postseason would be our best shot to break the streak in three decades (1986 saw three expansion teams in a four team tournament, and still couldn’t pull it off), but the odds were still only at about 22%. In honor of those odds, I’ve decided to look a little more closely at the math behind this momentous occasion.
First, it’s interesting to look back at those odds; 22% was our best chance at the start of October in years, and yet, in the abstract, it doesn’t seem that great. Assuming each team has an equal 1/30 chance of winning it all in Spring Training, we’d assume the chance of an all-expansion World Series in any given year to be 21.78%, just below the 21.875% I calculated back in September*. That’s 7/15 in the AL times 7/15 in the NL. And yet, somehow, it ranks as one of the best chances we’ve ever seen. Certainly within the top five, at least. Why is that?
*Note: Given the short series and random nature of the postseason, I rounded each team’s chance in a given series to 50%. For quick and rough calculations, that’s probably close enough. In any case, it fits in with my “assume each team has an equal chance” method that I’ll use for the rest of this article. Also, part of my reasoning for assuming every team has a 1/30 chance is that we’re not dealing with a specific year, but any random year. For example, if I told you we’d have 30 teams still in the year 2030, what odds would you assign each team lacking specifics? Given that we haven’t quantified the effect of being an expansion team, setting each team as equal seems reasonably fair. Since we’re essentially assigning the 2015 odds with 1960 knowledge for most of the piece, this seemed like a fair estimation.
I really can’t say for sure. I mean, we all kind of know that expansion teams have a rougher go of things than either league’s original eight. There are probably specific underlying reasons for that, and hopefully someone has looked into it more extensively. All I’ll be doing here is showing how rough it’s been for these underdogs.
So, assuming that every team has an equal chance of winning the World Series in a given random year, what were the odds it would take us until 2015 to get only expansion teams? What I did was look at the league’s make-up each year, in terms of expansion and non-expansion teams, just like I did earlier. I did this for each season since MLB started adding teams way back in 1961. Then, I took to probability of an all-expansion series each season and multiplied it with the previous years. Basically, what I wanted to figure out was: if you were told in 1960 how the league would expand in the next five and a half decades, what would the chances be that it would take until 2015 for two of them to meet at year’s end?
In the end, through 2014, those odds came down to 0.018%. In fractions, that works out to less than 1/5000 (and yes, that’s removing the 1994 postseason that never was). Is this a reasonable estimation? I mean, if we could quantify how expansion teams are disadvantaged, it would probably be a little less surprising. At the same time, though, I’m not sure that it would explain everything. I mean, over half of the first eight expansion teams from the 1960s still haven’t won a World Series. Is that all due to the pains of being an expansion team? The Astros, Rangers, Padres, Nationals, and Brewers are all fifty years old or getting close; can they still point to the fact that they’re an expansion team as the cause of their woes? I really don’t know. Whether it’s dumb luck or a sign of how disadvantaged these newer teams are, it’s an interesting fact.
Let’s look at it a few different ways, though. Less than half of the fourteen expansion teams have won a single World Series (past champions are the Mets, Royals, Blue Jays, Marlins, Diamondbacks, and Angels). Only three have won it all twice (the Mets, Blue Jays, and Marlins, which is quite an interesting group). It seems fitting that our first all-expansion series comes down to the Mets and Royals or Blue Jays, in a way; the Mets or Jays would become the first three-time champion, while the Royals could become the fourth repeat winner. Additionally, those three were the first three expansion champions (the Mets in 1969 and 1986*, the Royals in 1985, and the Blue Jays in 1992 and 1993).
*Note: When you look at it this way, it seems kind of funny that the Mets have the reputation that they do. They were the first expansion team to win it all, no expansion team has more titles or as many pennants (5; only the Royals have more than 2, and either they’ll get number 4 or the Blue Jays will get number 3), their success has been pretty spaced out (pennants in 1969, 1973, 1986, 2000, 2015, NLCS losses in 2006, 1999, and 1988), etc.
Which brings up another interesting point; we were in the second longest expansion-champion drought ever. The 2003 Marlins were our last one, twelve seasons ago. The only longer dry run for expansion teams was between the first two, from 1969 to 1985 (sixteen seasons). The drought from first expansion team to first expansion champion was even shorter than that (1961 to 1969). With those three extended droughts, you could probably deduce that eight of the ten expansion titles (counting this year) came in a nineteen year span (which included 1994, so it was only eighteen seasons). What caused that approximately-two-decade burst? Again, no idea.
Which gives me one last interesting pieces of trivia: how many expansion World Series should we have “expected” for expansion teams? Again, we’ll use the assumption that every team has an equal chance in a given year. Given that, the expected value for a expansion team winning the World Series in a given year is about .467 (which equals 14/30). Essentially, since about half the league is expansion teams, you’d “expect” an expansion team to win about every other season.
Except that there haven’t always been fourteen expansion teams. Once we account for the gradual growth over time, we come out to about 20.44 “expected” titles for these new teams. In real life, we’re at only 10 (counting this season). For pennants, we find something similar; there “should” be 40.68 pennants for expansion teams, yet we’re only at 22. Is this a quantification of the effect of being an expansion team? That you’re half as likely to win the World Series in a given year in perpetuity? Again, I’m not sure, but it’s an interesting result nonetheless.
A few more notes that don’t fit in elsewhere: No expansion team has more World Series titles than a non-expansion team. The Mets or Blue Jays would be the first, and they’d pass the Indians, Cubs, and Phillies. The Mets’ 2015 pennant ties them with the Indians with five; again, none of the original sixteen has fewer than that. The Royals winning this year would become the second expansion team with four pennants, while the Blue Jays would be only the third with three. The Ranges and Padres are the only other expansion teams with more than one. The only two teams without a pennant are expansion teams (the Mariners and Nationals). Also, expansion teams are well-represented in the overall title drought department. While none of them can match the Cubs or Indians, the next six longest active droughts are all expansion teams who have never won (the Rangers, Astros, Brewers, Padres, Nationals, and Mariners).
Whatever happens the rest of the year, history has been made. Here’s to an exciting rest of the season.