To get a true measure of baseball players and teams, many advanced statistics are park adjusted. What exactly does that mean and how is it done? Mark and Andy dive into the many layers of park factors to find out what goes into them, how different sites calculate theirs, and the pros and cons of using them at all. This week's Roll The Stat is a park factor guessing game--which historical stadiums have been hitter-friendly and which have been nicer to pitchers? Some parks have the effect you would expect, while others are a bit more surprising.