With the MLB regular season in the books, let's take a look at a measure of competitive balance using 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.
From the 2016 MLB regular season, we see that the American League had a competitive balance of 1.586 and the National League had a competitive balance of 1.713, meaning that the National League was less competitive than the American League. Overall, MLB had a Noll-Scully of 1.657, 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.