Changes Are Coming to Coors Field

Any opportunity to talk about Coors Field is a good opportunity, and, hey, wouldn’t you know it, but the Rockies’ home ballpark is undergoing some alterations that’ll have an effect on the gameplay. I’ve only just heard about them, but they’re relatively uncomplicated, and they should be in place in time for the start of the regular season. Baseball’s best argument against the idea that high-scoring baseball is exciting baseball is about to feature some higher fences.

I’m kind of a dork about park effects, and that’s why I find Coors so fascinating in the first place. They’re always trying to figure out if it’s possible to play some sort of normal baseball at altitude, and now we can get into the latest thought, as provided by Nick Groke. The Rockies are working to reduce the number of cheap dingers. It won’t not work. That much we can already say.

About the higher fences — here’s the critical information:

The Rockies will raise their outfield wall between right-center and right field by 8 feet and 9 inches, to match the height of the out-of-town scoreboard, at 16 feet-6 inches in height. A green-coated, chain-link fence will sit on top of the existing green-padded wall in front of the visiting and home bullpens.

The outfield wall height also will increase down the left field line, by 5 feet, to 13 feet. That extended fence will be in front of the tunnel next to the bleachers.

The change in right field is going to be a great deal more significant than the change in left field, but in case you’re having a little trouble visualizing all these, here is some help. The right-field situation:


And, the left-field situation:


You’re talking about a smaller height increase in left, over a smaller distance. In right, they’ll be raising the fence in front of both of the bullpens, matching the high wall more down the line. There’s no way for this to not decrease the number of homers. That part, in general, is set in stone, and what’s left to wonder is the magnitude of the change.

Sure, I could try to work something out from here, but look, I don’t need to! The Rockies have gone to the trouble, and this is from a little later in the article:

The Rockies, Bridich said, determined that right-center field and down the left field line were high-home run areas. They used a formula that accounts for the launch angle and exit velocity of hits off the bat to figure out how to reduce easy homers. By that measure, total home runs at Coors Field could fall by 5-6 percent.

Let’s work with a 5% decrease. I’ll trust the Rockies on this one. And clearly, Coors Field has been inflating homers — over the last five years, Rockies home games have featured 983 dingers, while Rockies road games have featured 743 dingers. I know that the Rockies play a lot of road games in pitcher-friendly environments, and I know that Rockies hitters struggle to an unusual degree when they’re away from home, but that gap is enormous, and the bulk of it is the Coors effect. If we take away 5% of 983, we get 49 homers. Let’s think of those as 49 homers that wouldn’t exist. Carlos Gonzalez thought of one homer in particular that wouldn’t have been a homer with a higher fence:

What’s going to happen here, in terms of how Coors plays? Some home runs will go away, surely. By the estimate above, working retroactively, we would’ve taken away 49 homers over five years. Already you might be able to see that’s not really that much of a decrease. But there’s even more here, because it’s not like those batted balls suddenly become un-valuable. I have to imagine every single would-be home run affected by this will instead turn into a double or triple. It’s not like they’re going to turn into outs. And doubles and triples are worth a pretty big fraction of the value of a homer.

Just keeping the same ratio as has been established, we’re looking at what would’ve been 49 fewer homers, 42 more doubles, and seven more triples. Using the league-average figures from the last five years, the run value of a homer is 1.65, the run value of a triple is 1.27, and the run value of a double is 1.00. Running the basic math, you lose 81 runs by subtracting the homers, but you gain back nine runs with the triples, and you gain back 42 runs with the doubles. Which means it would be a reduction of 30 runs, in all. That’s over five seasons. I’m just running estimates here, but a few points in either direction won’t change anything significant. Here’s what’s actually happened: there have been 11.3 runs per game in Rockies home games, and 7.9 runs per game in Rockies road games. Using the math above drops that to 11.2 runs per game in Rockies home games.

It’s something, for sure. Every pitcher in the world would rather allow a double than a homer. But this pretty clearly shouldn’t be a game-changer, except in the most literal sense of the word. Every so often, a would-be homer will instead be a double or a triple, but doubles and triples are still valuable. It’s not like the Rockies are over-selling this; they know they haven’t solved Coors Field with some higher fences. But you get to see how difficult a project it is to try to make Coors work like any other ballpark.

The home runs are part of it, absolutely. Normalizing Coors Field means normalizing homers, and this’ll be some kind of small step. But there are other huge issues:

BABIP, last five years

  • Rockies home games: .333
  • Rockies road games: .297

K%, last five years

  • Rockies home games: 17.1%
  • Rockies road games: 20.6%

I don’t know what you can do about the strikeouts, since pitches just move differently in Colorado and since hitters are more incentivized to make contact. And the BABIP in large part comes from the gigantic size of the outfield, which you need to try to keep homers down. Raising the fences actually only makes the BABIP issue slightly worse, which counters the home-run drop. Coors Field is complicated. You know all this. Maybe it’s not that much of an issue in the end, but it’s a big giant outlier that can make it difficult to attract, develop, and/or keep organizational talent.

The Rockies know they aren’t fixing that much here. They might go on to do more later on. We’ll just have to see what adjustments they might decide to make down the road, but for the time being, maybe this’ll make pitching in Colorado ever so incrementally less unpleasant. No one wants to give up a double off the wall, but when you have to pick between that and a stupid cheap homer, you’ll take the two bases, and maybe you curse just a little more under your breath.

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.

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I’m going to have to disagree with the “any opportunity to talk about Coors is a good one”. This article was useful, but about 90 % of the time Coors is simply used as an excuse for lazy analysis.