Another Look at the Coors Conundrum

Coors Field
Isaiah J. Downing-USA TODAY Sports

Since joining MLB as an expansion team in 1993, the Rockies have won 46.9% of their games. Among active franchises, that mark stands as the third worst. Granted, most other teams have had a lot more time to establish themselves, and the Rockies have bested their 1993 expansion counterparts in the Marlins (though given the option, they’d probably take the Marlins’ two World Series championships). But they have also been handily outpaced by the 1998 expansion teams, the Diamondbacks and the Rays, who have each posted winning percentages of 48.5%. Further, the Rockies still have the fifth-worst winning percentage even if we limit our scope to 2000 onwards. These results don’t line up with the Rockies’ spending, especially as of late, which has placed them in the middle of the pack in terms of payroll — that is, until we consider the Coors effect.

The Rockies’ pitching has long dragged down the fortunes of the team as a whole. Since 2000, they’ve easily been the worst staff in the majors with a 4.93 ERA. But it isn’t entirely their fault: pitches move sub-optimally and balls fly further in Colorado. The front office has tried various remedies, in particular opting for more groundball-heavy or low-BABIP pitchers. Neither of those strategies has worked all that well, but some proposals carry promise, like the idea of relying more on gyro spin and/or using the lesser impacts of Magnus force in Colorado in an advantageous way.

But the innovation in Denver appears to be at a bit of a standstill, possibly due to unrealistic expectations about the Rockies’ current level of competitiveness. Self-evaluation issues aside, on a recent episode of Effectively Wild, Ben Lindbergh and Meg Rowley described the Rockies as a team that could theoretically be more consistent if they truly figured out how to navigate playing half of their games at Coors. That got me thinking, and while I certainly don’t purport to provide the final answer, I do hope to supply a different perspective on the problem.

During the last several weeks, I’ve written a lot about swing decisions: First-pitch swing decisions and how they’re influenced by the previous hitter’s result, two-strike swing decisions and how they relate to loss-aversion, and even a bit about swing decisions after hard-hit foul balls. What about when it comes to Colorado? Upon arriving in the most hitter-friendly park in the big leagues, do batters change their approach in order to be more aggressive?

On my journey to answer this question, I first looked at the Rockies themselves. I figured that those donning black and purple would see the largest changes in approach going to and from Colorado, given their acute awareness of the extreme run-scoring environment there. In case you’re wondering, they began using a humidor in Coors starting in 2002. Given that I needed pitch-tracking data, which on Baseball Savant goes back to 2008, in order to assess approach, the initial implementation of the humidor didn’t have any impact on my sample — it probably wouldn’t have anyways because it had little effect on offense. The Rockies did opt to raise their walls prior to the 2016 season, so I included separate rows for that period. I also excluded 2020 because of the short season and lack of fans. Here’s what I found:

Rockies Home vs. Away, 2008-2022
Split wOBA Swing% SwStr% O-Swing% Z-Swing%
Home 0.362 47.6 10.4 28.2 67.7
Away 0.293 47.7 11.8 30.3 66.1
Home (2016-22) 0.360 48.5 11.5 28.5 68.7
Away (2016-22) 0.290 48.6 12.6 30.7 67.6

The wall-height increase didn’t really change things; the post-wall Rockies just swung more across the board. Unsurprisingly, there’s always been a massive home-road split in terms of wOBA. That can largely be chalked up to the decreased pitch movement and jumpier batted balls in Coors (though the Coors hangover likely played a role too; more on that later). The Rockies did have a noticeable improvement in plate discipline at home, chasing less and swinging at more strikes, which may have led to a lower swinging strike rate. This might also have been because of the decreased movement, which renders pitches more trackable. Their overall swing percentage, however, remained virtually identical at home and on the road.

Strangely, Rockies hitters saw more pitches in the zone at home (49.2% to 48.6%). My first thought was that pitchers might be having trouble with their command, allowing certain offerings to leak over the plate unintentionally due to their newfound lack of movement. That might still be a possibility, but more likely, it’s because the Rockies were ahead in the count more often at home (27.5% of the time to 26.1%). Pitchers throw in the zone more often when hitters are ahead:

The Importance of Count
Split wOBA Swing% SwStr% O-Swing% Z-Swing% Zone%
H-Ahead 0.423 50.1 9.9 28.1 67.7 55.6
P-Ahead 0.224 51.5 13.3 33.6 79.8 38.8
Even 0.303 40.8 9.3 24.5 56.8 50.3

This can also explain the improvements in discipline to some extent, as the O-Swing and Z-Swing rates ahead in the count closely resemble those of the Rockies at home. Even controlling for count didn’t result in a meaningful change in the home-road Swing% or Zone% split, though, indicating a pretty uniform approach according these metrics across environments.

Back to the drawing board. If the Rockies didn’t meaningfully change their approach when they arrived at Coors, did their opponents? In other words, did they treat Coors like a special kind of away game, or did they treat it like any other?

Non-Rockies At Coors vs. Away Elsewhere
Split wOBA Swing% SwStr% O-Swing% Z-Swing% Zone% H-Ahead%
Coors 0.344 46.9 10.2 26.7 67.3 49.7 27.9
Elsewhere 0.311 46.5 10.8 28.7 65.4 48.6 27.1

They didn’t change any more than the Rockies themselves: There were similar improvements in plate discipline as well as similar jumps in zone rate and hitter-ahead rate. There was a slight increase in swing rate, but not enough to be meaningful.

It seems like hitters don’t really jump at the chance to play in Coors, at least not in a way that shows up in their approach. But while the Rockies and their opponents didn’t meaningfully differ in how they changed their approach upon arriving in Colorado, they differed in how the environment impacted their performance.

Coors is thought to inflict a “hangover” on Rockies’ players upon their departure from Denver. They have a ludicrous home-road split in terms of winning percentage: at home, they’ve been the 12th-best team since their founding, while on the road, they’ve been the flat-out worst. It’s possible that in trying to figure out what works at Coors, the Rockies’ front office has neglected to amass the kinds of players who perform well everywhere else. But there’s also a real adjustment period that seems to occur when the Rockies embark on a road trip. Prior to the 2020 season, Charlie Blackmon spearheaded an effort to try and remedy this, centered around more game-like batting practice, but the Rockies haven’t made real progress since then. Their 2021 saw a near-historically large home-road split, and last year, they had the 18th-best record at home and the second-worst on the road.

The 18-point gulf between the Rockies’ home wOBA (.362) and that of their visitors’ (.344, five percent lower) since 2008 is substantially larger than the league-average home-road gap of 11 points (3.4 percent lower). It’s also the ninth-largest gap in that time span. The percentage differences indicate that this isn’t just a byproduct of higher overall wOBAs, but if you needed more proof, consider the Reds’ Great American Ball Park.

While Coors is leagues above all other stadiums when it comes to being a hitter haven, according to our park factors, GABP is in a tie with Fenway for the second-highest basic factor, meaning it’s the second-most hitter friendly. It also has the highest home run factor given its bandbox dimensions. But the Reds’ wOBA at home bests that of their visitors by just two points.

And it’s not like the Reds have been worse than the Rockies; in fact, their winning percentage during this span has been six points higher. There’s either something about adjusting to Coors that widens the host-visitor gap, or the Rockies have done a good job of finding players who really do perform better than expected at Coors (whether or not they can perform on the road). All of the gaps larger than the Rockies’ belong to the best performers of the past 15 years, a group within which they don’t belong: The Dodgers, Yankees, Rays, Red Sox, Cardinals, Braves, and Astros. Meanwhile, the Reds are keeping company with the Twins and Padres, whose winning percentages have been more in line with their own.

One more thing that looking at GABP keyed me in on was that the improvements in plate discipline there were much less pronounced than those at Coors. This despite the Reds having a home-road split in hitter-ahead rate similar to that of the Rockies:

GABP Home vs. Away
Split wOBA Swing% SwStr% O-Swing% Z-Swing% Zone% H-Friendly%
Reds Home 0.326 47.1 11.1 28.2 67.4 48.2 27.3
Reds Away 0.305 47.6 10.9 28.8 67.3 48.7 26.3
Away Teams @ GABP 0.324 46.5 11.2 28.7 65.9 47.7 27.4
Away Teams Overall (Minus Coors) 0.311 46.5 10.8 28.7 65.4 48.6 27.1

The similarity of the hitter-ahead rate changes for the Reds and Rockies implies that the strange pitch movements in Coors aren’t a major factor in pushing the count in favor of the hitter. Rather, pitchers might just fall behind more often when they’re not at home because they’re in an unfamiliar environment with hostile fans. Vice versa for the hitters, who have an easier time settling into the box when they’re at home.

To come full circle, there weren’t any meaningful changes in swing percentage when entering Coors or GABP, putting my aggression theory to bed. What’s more, even the improvements in plate discipline at Coors are looking like they have little to do with the field’s hitter-friendly nature, given that we didn’t see the same improvements at GABP. At the same time, while the magnitude of the changes in plate discipline differed for the two stadiums, that of the changes in hitter-ahead rate did not. This makes me think that hitter-ahead rate might not be responsible for the plate discipline improvements at Coors after all; the strange pitch movements are. So while Coors’ status as a hitter’s haven doesn’t cause a change in approach in and of itself, one of the attributes that makes it a haven does. Only time will tell whether pitchers’ offerings will leak out over the plate more often in Colorado forever or if they’ll be able (and willing) to use these findings to their advantage somehow.

Alex is a FanGraphs contributor. His work has also appeared at Pinstripe Alley, Pitcher List, and Sports Info Solutions. He has a degree in psychology and cognitive science from Vassar College, with minors in economics and philosophy. He is especially interested in how and why players make decisions, something he clearly struggled with when determining his course of study in college. You can find him on Twitter @Mind_OverBatter.

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3 months ago

Why don’t the Rockies try moving the fences in to normal depth and making the wall 50 feet high all around?

Would eliminate many of the bloops and turn a lot of HRs and triples into doubles. Certain outs would now be balls off the wall, but it seems worth a shot

Last edited 3 months ago by theflusher
Roger McDowell Hot Foot
3 months ago
Reply to  theflusher

IMO they should just build a pressurized dome over the stadium

3 months ago
Reply to  theflusher

No, that would turn way too many outs into doubles. The number of overall extra base hits would wind up being even more ridiculous than before the Humidor.

Smiling Politely
3 months ago
Reply to  theflusher

Let’s go full Polo Grounds in Denver

3 months ago
Reply to  theflusher

One thing is certain. It’s too tough to have the outfielders cover that much ground at that altitude. Altitude is the big elephant in the room. The Dodgers moved their AAA out of Albuquerque bc it made it too difficult to get a true sense of the players skill.