As I was making corrections to the baseball program the other day I got to wondering about ballpark effects. We know they exist but how much effect do they have on a teams performance. So I came up with a way to calculate a ballpark inflation/deflation factor. Looking at values from 2008 as an example I found Texas’ ballpark inflated runs by about 15% while San Diego deflated runs by about 20%. So the numbers were not very surprising. The biggest inflating stadiums were Texas, Colorado, and Arizona. The biggest deflators were San Diego and Los Angelos Dodgers.
So I have added a couple of new columns on the projection page that multiply the visiting teams/pitchers numbers by this ballpark factor. (the home teams already have it included by definition). It will be interesting to see if it makes a difference. It may need some time to stabilize because I am using only season to date data to calculate it.
Update: I tried searching the internet to see if what I came up with was similar to what was already out there, and it turns out you can find the exact same formula at ESPN.