01 November 2017

MLB Postseason 2017: One. More. Game.

We've been spoiled of late. The 2017 World Series will go seven games. The Series went seven last year too, and in 2014, and in 2011. That's three out of the past four years and four out of the past seven. The current flourish of winner-take-all championship baseball follows an eight-series drought from 2003 through 2010, in which not one World Series went the full seven.

Total of Games Played in Each World Series since 1903

Both the flourish and the drought are uncharacteristic. More series have gone seven games than have gone only six, five or four since the World Series adopted the seven-game format in 1922. Nevertheless, it's a less-than-even proposition: 39% of series in the best-of-seven era have gone the distance.

Frequency of Total Games Played in World Series during the Best-of-Seven Era

So let's savor tonight and keep in mind the lean times when baseball events like tonight's seemed rare. This year's seventh game pits the favored Los Angeles Dodgers against the never-say-die Houston Astros, who have faced adversity before in this postseason. This is it.

World Championship Probabilities by Playoff Team over Time

My model, which (reminder) does not take into consideration lineups or pitching rotations, calls the Dodgers 56% favorites to win it all for the first time since 1988 and the Astros 44% underdogs to win their first ever title. FiveThirtyEight, which adjusts for pitcher quality, gives the Dodgers a bigger edge at 60-40%. The bettors at Bovada agree with Nate Silver & Co. this morning, selling LA at -162 and Houston at +141 (which, when discounting the vigorish, works out to about 60-40).

Estimated Probability of Discrete Series Results

At the start of the series, a Dodgers win in seven was the second most likely outcome at 18%; Astros in seven was the third most likely outcome at 14%.

This will conclude my regular coverage of the probabilistic wends and turns of the 2017 MLB Postseason. Check back soon for a review of my projections and the winner's path to baseball immortality.

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