There’s nothing at all strange about a city the size of Denver having a major-league baseball team. I’ve been to Denver. Not only is it big enough to have multiple gas stations — it’s big enough to have multiple kinds of gas stations. Where things do get strange is in the details. Denver, of course, is really high up, relative to where sea level is, and that makes for an unavoidably different baseballing experience. There’s nothing, really, to be done about it. Baseball in Denver’s played at altitude, so baseball in Denver’s a different sort of baseball.
Things happen differently there, and for that reason Denver’s a perfect case for why park factors have to exist for analysts to get anywhere. It’s simply an extreme hitter-friendly run environment. Now, when it comes to games in Denver, everyone, at least, is on a level playing field (literally!) (figuratively too). But there are games played outside of Denver, and additionally, there are players who are removed from Denver. Whenever a position player leaves the Rockies, people get worried that he’s going to fall apart, because he’ll miss the lopsided circumstances. With players who used to play in Colorado, there’s a tendency to be cautious, and perhaps even skeptical.
This could be observed after the Astros traded for Dexter Fowler. Not that Houston is going to slap Fowler in the face with a pitcher-friendly run environment, but Houston isn’t Colorado, and Fowler has big career home/road splits from his time with the Rockies. At home, he’s posted a .384 wOBA. Away from home, that’s dropped to .312, and there are plenty of people who believe his offense was just a product of the environment. This always happens when talking about Rockies. People are just disinclined to trust people who play and hit as Rockies.
Admittedly, I’m one of the wounded ones. As a Mariners fan, I experienced what became of Miguel Olivo after he left the Rockies. More memorably, I’ll never be able to forget the Jeff Cirillo catastrophe, and that one seems obvious in biased retrospect. Cirillo, with the Rockies, only really hit at home. So why would anyone think he’d hit in Seattle? What a terrible decision! But this isn’t analysis. Not worthwhile analysis, anyway.
Better to see what’s happened with groups. The Rockies have played in Coors Field since 1995. They’ve played full seasons in Coors Field since 1996. Since 1996, how have position players done after leaving the Rockies? How have they done staying with the Rockies? This should tell us more than individual anecdotes. Jeff Cirillo shouldn’t be considered representative of anything.
I looked for players who batted at least 250 times in consecutive seasons, and who spent the first of those seasons with the Rockies. I then grouped them by where they spent the second seasons, with the groups being “Rockies” and “not-Rockies”. Of the pool, 92 players stayed with the Rockies for both years. Meanwhile, 28 players moved on between seasons. I excluded guys who were traded from the Rockies during the second year, but I kept guys who were traded from the Rockies between years.
Let’s have a good time, now, with the data. We’ll start with the guys who stayed as Rockies, so as to build suspense while establishing something of an approximate control.
- .370 wOBA
- 109 wRC+
- 2.5 WAR/600
- .363 wOBA
- 105 wRC+
- 2.1 WAR/600
More or less identical numbers, with hints of a very slight overall average decline. Now let’s look at the guys who left the Rockies between seasons. How much did they end up missing Coors Field?
- .336 wOBA
- 87 wRC+
- 1.1 WAR/600
- .319 wOBA
- 92 wRC+
- 1.7 WAR/600
The players, on average, lost some points of wOBA, but then we’d expect that, and wRC+ corrects for that, and we actually see a wRC+ improvement. Same goes for full-season WAR. These players survived just fine. Obviously, there were guys who struggled, like Cirillo and Olivo, but then you have, say, Andres Galarraga. Or Matt Holliday. Chris Iannetta was the same hitter in Colorado and in Los Angeles. Seth Smith didn’t lose very much. And this data doesn’t include Larry Walker, who the Rockies traded in the middle of 2004. Walker hit well in St. Louis for a year and a half before he had to hang up his cleats.
Presumably, part of what we’re seeing is regression to the mean. Some of the players who left Colorado might’ve been doing so after performing unusually poorly, so we’d expect a bounceback. What we don’t see is any evidence of devastation, post-Coors. Yeah, there are individual cases of guys who couldn’t hack it anymore after leaving Colorado. But sometimes players just get worse. Garrett Atkins got progressively worse with the Rockies. Juan Uribe was dreadful in his sophomore season before taking a step forward, and then taking another step forward after joining the White Sox. Basically: we have park effects, and park effects seem perfectly able to make sense of Rockies position players. They play in a weird environment half the time, but taking that into account is what math is for.
Certainly, you can never be sure of a guy. The Astros can’t be sure that Fowler is going to adjust well to a new park. But you can never be sure of a guy under any circumstances, and Rockies players might just make people unusually aware of that fact. In fairness, they do spend half the time facing pitches that move differently than they would around sea level. But that’s a big part of why Colorado’s road numbers tend to look kind of lousy. Their home-field advantage sort of causes a road-field disadvantage, and then when you remove players from the team, they don’t have to worry about pitch-movement adjustments so much anymore. They can just hit curveballs that always move like regular curveballs. Historically, there’s a greater number of position players who did fine leaving Colorado than position players who didn’t. You can’t let Jeff Cirillo or Vinny Castilla stand for too much.
To close with a general idea: home/road splits tell you a lot about what’s happened. But wRC+ tells you more about what’s going to happen. Sometimes a player really might be a product of his environment, but those cases are less frequent than one can be led to believe.
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