So, for the past 6 months, everybody has been talking about how the 2004 Red Sox made the "greatest comeback ever." Every time I hear that, it bugs me - and not just because I'm a Yankees fan (but mostly because of that). It's bugging me because I'm wondering, is that truly the most improbably comeback in postseason history?
Purely statistically, I don't think it is.
I have this excel spreadsheet I got from somewhere (I'll try to take the time to find the site later) that gives Win Expectancies for a team in any situation in the game. If you don't know, Win Expectancy is the chance a team has of winning a game in any situation. Say you wanted to know the odds of a home team winning a game when they were batting in the 3rd inning with a runner on 1st, 2 outs, and up by 1 run - this chart would tell you the probability of the home team winning was .738.
Anyways, what I did was to figure out the chances of the Red Sox winning the 2004 ALCS, down by one run in the bottom of ninth with 0 outs and 0 on, and down 3-0 in the series.
The odds of them winning game 4 in that situation were .189. Then, multiplying that by the odds of them winning game 5 from the outset (.589, since they were the home team), and game 6 and 7 (.411), and you get their total chance of winning the series to be .0188.
Obviously, quite small chances. But, it seems, not as small as you'd think.
For good measure, I compared it with another famous comeback - that of the 1986 Mets, down by 2 runs in the ninth inning or later, with 2 outs and nobody on, and down 3-2 in the series.
The Mets chances of winning the game in that situation were about .014. Multiply that by their chances of winning game 7 as the home team (.589), and you get .008.
So, statistically speaking, it would appear as the Mets comeback in 1986 was a more unlikely comeback.
I guess what I'm wondering here is whether people think this is a valid comparison. Obviously, this does not say that the Mets comeback was necesarrily greater - it does not take into account alot of other things, such as the mental barrier that seemed to have existed around 3-0 deficits, etc.
But it's an interesting thought. I may try, later, to plug in some other famous postseason comebacks and see what comes up.