With the 2017 MLB regular season finished, let's take a look at competitive balance using the Noll-Scully measure of competitive balance. The Noll-Scully uses the actual standard deviation of a league's winning
percentage and compares it to a league if wins and losses were randomly
determined in a statistical sense. A Noll-Scully of 1.000 indicates
wins and losses were randomly determined and thus the league is
perfectly balanced in a competitive sense. A Noll-Scully higher
indicates that the league is less than perfectly balanced. As the value
increases the league is less competitive.
For the 2017 MLB regular season, we see that the American League had a
competitive balance of 1.658 and the National League had a competitive
balance of 1.897, meaning that the National League was less competitive
than the American League. Overall, MLB had a Noll-Scully of 1.783,
which is slightly more competitive than the league average Noll-Sculy
since 1982.
If you are interested in doing this on your own, here is a step-by-step guide to calculate the Noll-Scully measure of competitive balance using Microsoft Excel.