2013 Park Factors Updated
We’ve updated the site with 2013 park factors, which you can see on our FanGraphs Guts! page. These will be updated daily for the rest of the season and we will have the more granular park factors for 2013 updated shortly (on a weekly basis) as well.
To explain a little more about our park factors, we use up to 5 years of data to calculate park factors using Patriot’s method. When a park makes significant changes to their layout, or it is just a brand new park, we use only data from the changed or new park.
In the case of Safeco Field and PETCO Park, which had significant fence movement, we are only using 2013 data to calculate the park factors. With just this season’s worth of data, the park factors for these parks are being heavily regressed (90% towards 100, a neutral park).