This article is part of our The Z Files series.
One of the first things I do when the season ends is run park factors. Part of it is practical, as they're needed for 2019 projections, but they're also fun to look at. Other than checking out the parks at the extremes, several venues piqued my curiosity. Front and center is Chase Field and the effect of the humidor. Another is SunTrust Park, as we now have a second season of data. Similarly, this is the second year Minute Maid Park played without Tal's Hill. Finally, one of the under-the-radar changes was Angel Stadium lowering the home run line in right field from 18 down to eight feet.
Before reviewing the 2018 factors, keep in mind applied park factors are three-year averages to flesh out the residual variance. The algorithm is designed to minimize the influence of the team by comparing hitting and pitching results home and away. That is, a hitter-friendly park isn't a result of a strong offense or weak staff, while a pitcher-friendly venue isn't due to a solid rotation or punchless lineup. Further, a venue favorable for homers isn't necessarily advantageous for runs, while a power-suppressing venue can be a boon for runs if it means more balls finding outfield grass. For a more comprehensive description of park factors, check out a piece I wrote in April 2017, The Necessary Evil of Park Factors.
Another important thing to understand is that park factors do not apply to all players in a linear fashion. Plus, when