After this year's dramatic World Series, I took a look at how competitive recent World Series have been. While there isn't a standard method of evaluating competitiveness, I looked closely at a couple of factors that I thought could serve as proxies for competitiveness. I posted this on my blog a couple weeks ago - thought I'd share it here as well. As always - I'd love to get some feedback.

This year’s World Series has been referred to by many as one of the best World Series in recent memory. While the claim was pretty apparent to anyone who watched it, it led me to consider the competitiveness of recent World Series. In order to get a historical perspective, I began by looking at the average number of games played within each World Series by decade over the past 100+ years.

For four straight decades, between 1940 and 1979, the average number of games played in the World Series was above 6 per World Series, by far the highest of any decade or stretch of decades. In the last four decades, average World Series length has fallen each decade from a high of 6.100 in the 70s, to 5.900 in the 80s, to 5.556 in the 90s, and finally, to 5.417 in the 2000s. A decline in average World Series length could signify a decrease in World Series competitiveness.

I then looked at leverage index (LI) which is a measure of the importance of a particular situation in a game. Average LI is 1, and is considered a neutral situation. An LI greater than 1 signifies a more important situation than an LI of 1, and an LI of less than 1 signifies a less important situation that an LI of 1. I used LI as a proxy for competitiveness. By looking at the average of the average LI (aLI) of each game in the series, we can get the average importance of each situation in a given World Series. 

The average aLI of all of the World Series games played between 2002 and 2011* is 1.023, or approximately 1, which is neutral. Based on the above figure, six of the ten World Series had an average aLI of less than 1, two had an average aLI of slightly greater than 1, and two had an average aLI significantly greater than 1. According to my average aLI method, the 2005 World Series between the Houston Astros and the Chicago White Sox had the highest average importance per situation, (aLI = 1.560), followed by this year’s World Series, (aLI = 1.201).

The final analysis puts the variables behind the two prior analyses together. I graphed the average aLI and series length by World Series to see how the two variables mapped onto each other.

While the most competitive series would be a long series with an average aLI above 1, a shorter series with a high average aLI could be more competitive than a long series with a low average aLI. Since both series length and average aLI point to the competitiveness of a World Series, I wanted a way to incorporate both factors into one final measure of competitiveness. Since the two variables are independent of each other, I ended up multiplying the series length by the average aLI of the series to get the total aLI of a World Series. The higher the total aLI, the more competitive the series. Here are the results.

It’s quite apparent that the 2011 World Series ranks highest on the competitiveness scale. Not only did it have a relatively high aLI, but it also lasted seven games - seven games worth of high importance situations makes for a very competitive and compelling World Series. The 2002 - Giants vs. Angels - and 2003 World Series - Marlins vs. Yankees - were next in line in terms of competitiveness, with the 2004 World Series - White Sox vs. Astros - now placing fourth as opposed to first in my previous average aLI only analysis.

While aLI and series length are by no means perfect proxies for the competitiveness of a series, they are a good place to start. Further analysis could look at factors such as the number of lead changes, the number of games decided after the seventh inning, etc., to get to the heart of the issue of measuring competitiveness.

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*I limited the aLI analysis because I only had aLI data for World Series games between 2002 and 2011.