It is terribly unsexy to put together any kind of article about park factors. I know that; I’ve done it. But, here I am, for two reasons:
The meat of this is the following horrible-looking plot. I’m sorry that it looks so horrible but, what are you going to do about it? This post is already published. I slapped some numbers together using the Baseball Reference Play Index. For each year since 1994, I gathered numbers for Indians games in Cleveland, and I gathered numbers for Indians games not in Cleveland. Then I calculated some single-year “park factors” by just calculating ratios. Here are some of those ratios:
Arguably the most important one is the one tracking runs per game. I’m not the first person to see this. Tony wrote a couple relevant park-factor articles in September. But look at how that dotted line moves, after the stadium first opened. For a few years, the ballpark was somewhat hitter-friendly. Then it took a turn. Between 2003 – 2014, Cleveland reduced run-scoring by about 6%, with one odd offensive spike in 2007. That spike is important — there’s danger in trying to make too much out of single-year park factors. But look at the last two years. The park last year boosted offense by 26%. This year, 21%. Now we’ve got an extreme two-year park factor, that seemingly came out of nowhere. For a long time, the park was kind to pitchers. Somehow, lately, it’s played like a nightmare.
Batting average? Way up, relative to numbers in games outside of Cleveland. OBP? Way up. Slugging percentage? Way up. Batting average on balls in play? Way up. Slugging percentage on balls in play? Way up. Interestingly, also, the walk-rate factor is up, and the strikeout-rate factor has dipped. This year, the home-run factor took off, although last year homers in Cleveland were actually slightly down. That was made up for by a bunch of doubles.
Frequently, on FanGraphs, you come across posts that try to get at the answer to something. I don’t have answers here. Instead, I’m just raising a question. What’s been happening at Progressive Field, to drive so much offense over the past two years? Is this really just a random, yet randomly-sustained spike of statistical noise? Does this somehow have to do with the installation of the newer scoreboard? Has there been a bunch of high-rise construction in the surrounding area? Have wind patterns changed? Why has Progressive been so hitter-friendly? Because, based on the last two years, Progressive has been very hitter-friendly. I don’t know how that could impact the World Series coming up, but you could see some baseballs absolutely take off.
Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.
Nice work spotting this, Jeff. It’s been a topic of discussion among some of us Tribe fans. There were structural changes to Progressive Field before the 2015 season that included replacing thousands of outfield upper deck seats with boxy platforms and (I think it was then) removing an elevated walkway behind the outfield, so more than just the scoreboard has changed. It’s not at all clear those changes are responsible for the uptick in offense, though. Without controlling for weather conditions, we should probably be pretty conservative drawing conclusions.
It’s interesting to ponder, though. If Fangraph’s 5-year park factor is missing real changes to Progressive Field, it means the Tribe’s offense has not performed as well as wRC+ suggests, but also means its pitching may be better than we think.
I was just researching those renovations, scrolling through picture after picture after picture. Like you said, it’s not easy to draw a direct link between those park changes and the *statistical* park changes, but at least the renovations do fit the timeline. Something to monitor, if nothing else, in the year(s) ahead!