How Chase Field has changed as a park over the past decade.
Yesterday, I noted the way the D-backs pitchers had struggled on the road, with an era more than a run higher than at Chase Field. It got me looking at the park factors, and I was stunned to see Chase sitting 24th in the majors for home-run factor, by ESPN’s metric. [Other figures are available, but I like the way ESPN break things down] I mean, I expected the humidor to have had an impact since it was introduced before the 2018 season, but really? I know park factors are subject to fluctuation, so decided to take a look at a broader picture, covering the last decade. Below you’ll find the numbers for each season, covering the five pre-humidor and five post-humidor campaigns.
I’ll start by looking at the average numbers in bold from the pre- and post-humidor era (the latter is weighted for the shorter seasons in 2020 and 2022). You can see the humidor has helped drop Chase Field from an average rank of seventh, to virtually the middle of the pack at fourteenth, with a runs factor now only fractionally above average. It’s almost as interesting to note what hasn’t changed. Walks are almost the same, and the overall hit factor is only down about 1.6%. It is the breakdown of those hits which is radically different. Home-runs are, obviously, the biggest victim, going from 10% above average to 15% below. But doubles have dropped considerably more than triples.
This year though. Whoo. Look at the home-run factor: 37.5% below league average. Hits at their lowest factor since 2013, and triples even longer than that. Is it just a single-season aberration? Could be. Last year, Marlins Park had an HR factor which was lower still, at 0.582. This season, it has bounced right back to 0.960. So we could perhaps see the same thing happen at Chase Field. However, it is worth noting that this is apparently the first season humidors have been in use at all 30 parks; only nine did so for all of 2021. It’s also hard to separate park factors from all the other faffing around MLB has done, such as with the baseball themselves. Seems like something to keep an eye on, however.