Park Factor and Division-Wide Scoring Environments

Scoring in baseball is heavily influenced by environment. This is a natural facet of the game. When hitting a ball a particular distance results in a home run in one ballpark and does not in another, scoring will be different in those two parks. It’s further complicated by weather, fence height, and other, much more subtle factors.

This is accepted. We shrug when a 12-9 game happens at Coors Field. We expect home runs when the wind is blowing out at Wrigley Field. We speculate how the Green Monster will affect a new-to-the-Red-Sox pitcher’s results.

Advanced statistics adjust for this too, using something called “Park Factor” in a lot of calculations. Park Factor—at least the one featured on ESPN, where I got this data—is a rather simple number: it takes every game played at a specific ballpark over a season and compares the scoring in that game to the average scoring in all games played by those teams, then totals all games into one number. Here are the Park Factors, listed by team, averaged across 2018 and what’s been of 2019 (I cut out earlier seasons because Chase Field added a humidor prior to 2018).

Note: Values are adjusted slightly from ESPN’s values so they average out to 1.000.

When interpreting a team’s performance, this is, of course, only relevant for that team’s home games. And while park-adjusted statistics account for road games, too, I don’t account for them very well in my own head. So, since roughly 25% of a team’s games are played on the road against opponents from its own division, I thought I’d look at which divisions most favor scoring, and which most favor a lack of scoring. Here, then, are the averages for each of the six divisions:

Pretty consistent. Very consistent, in fact. Over a full season, the most scoring-suppressive divisions are only one and a half percent better for pitchers than a division of entirely average parks. No division is especially full of high-scoring or low-scoring environments. Which might not seem particularly interesting, but kind of is, as it means no team, it seems, is playing their road games in different enough environments, on aggregate, to look much beyond Park Factor when evaluating them.

Again, only kind of interesting. But could be good to know. Make of it what you will.