Fun with park factors: A follow-up

A few weeks ago, I published a piece looking at Park Factors, which had the robust Beyond the Box Score and sabermetric community at-large voicing their thoughts and concerns over the methodology used. Now, I'm going to attempt to right the wrongs I've committed.

One of the problems was that I didn't double the numbers; park factors are available on FanGraphs's Guts! page, but they're preceded by a little caveat:

All Park Factors have already been halved for use on full season stats.

I astutely overlooked this key note and proceeded to export the park factors to Excel without doubling them. Mitchel Lichtman — one of the authors of The Book — noticed this, and alerted me of it in the comments. He also brought another fallacy in the piece to my attention: Since the park factors are "running" (multi-year), a year-to-year correlation (which was included in the post) would be useless.

The largest lapse on my part, however, was failing to account for changes in the parks. From moving in the fences to installing different kinds of turf and/or grass to importing a humidor, ballparks aren't static, but my previous post gave the impression that they were. Two other commenters informed me of this; now, I've adjusted accordingly.

Below, you'll find the averages and standard deviations for all of the ballparks. Whereas there were 55 in the original article, there are 88 now, as alterations to the park have been considered. Moreover, these factors are all doubled, and will accurately reflect the stadium's effects.

If you know of any ballpark modifications that I've left out, feel free to notify me in the comments or on Twitter.

. . .

All statistics courtesy of FanGraphs.

Ryan Romano writes for Beyond the Box Score, the FanGraphs Community blog, and Camden Chat that one time. Follow him on Twitter at @triple_r_ if you enjoy angry tweets about Maryland sports and live tweeting about Community, Thursdays at 8/7c on NBC. Cool. Coolcoolcool.