Parity Comes to MLB

This is a guest post by Tom Ruane of Retrosheet

In looking at the standings the other day, I noticed that there
didn't seem to be many great or terrible teams so far this year,
especially in the AL, where most of the teams are within a
couple of games of .500. This got me to wondering if this was
out of the ordinary or simply something I hadn't noticed before.
To investigate this, I determined the difference between each
team's wins and losses after their first fifty decisions and
calculated the average difference to determine league parity.

Here are the seasons with the smallest average difference
after fifty decisions:

Year Teams Diff
1959 16 4.50
1944 16 4.88
1968 20 4.90
1975 24 5.00
1947 16 5.12
2011 30 5.27
1974 24 5.33

Not all teams reach their 50th decision on the same day, but to
get some idea of the early-season parity in 1959, see:

http://www.retrosheet.org/boxesetc/1959/06061959.htm

And here are the years with the least parity:

Year Teams Diff
1876 8 19.25
1884 28 15.86
1875 7 15.71
1879 8 14.50
1883 16 14.00
1872 2 14.00

And the same list since 1900:

Year Teams Diff
1907 16 13.00
1953 16 12.00
1911 16 11.62
1906 16 11.12
1955 16 11.12
1931 16 11.00

Here is a link to a 1907 standings page:

http://www.retrosheet.org/boxesetc/1907/06171907.htm

I also decided to look at parity by league. Here are the leagues
with the greatest parity after 50 decisions:

Year LG Teams Diff
1944 AL 8 2.50
1959 AL 8 3.00
1974 AL 12 3.00
1947 AL 8 3.50
1915 NL 8 3.75
1932 NL 8 3.75
1968 NL 10 3.80
1926 NL 8 4.25
1943 AL 8 4.25
1983 AL 14 4.29
2011 AL 14 4.29

A link to a 1944 page:

http://www.retrosheet.org/boxesetc/1944/06141944.htm

And the leagues since 1900 with the least parity:

Year LG Teams Diff
1907 NL 8 15.25
1903 NL 8 13.50
1906 NL 8 13.00
1946 AL 8 12.75
1913 AL 8 12.75
1955 AL 8 12.50
1909 NL 8 12.50

So the current year is nothing too earth-shaking, but I was
hoping some might find this interesting anyway.