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With 14 wins and 8 losses, the Colorado Rockies are off to one of their best-ever starts to a season. They lead the NL West, and they’ve more than doubled their playoff odds since the preseason. (Their odds are now 34 percent, according to FiveThirtyEight’s MLB predictions.) For a franchise that’s made only three postseason appearances in 25 seasons, an April like this is enough to make fans storm the field in excitement. But to keep this hot streak going, the Rockies will have to break the curse of Coors Field — and not the one you hear about all the time.
Coors Field is often discussed as a pitcher’s nightmare. That’s because baseballs don’t behave the same way in Denver’s thin air as they do at essentially every other major league park. They break less sharply, and they carry further when walloped; in turn, this leads to more hits, more homers and generally more run-scoring than usual.
But the thankless task of high-altitude pitching isn’t what’s been holding Colorado back for the last quarter-century. Paradoxically, the Rockies have had a far bigger problem with their offense over their time in MLB — specifically, how their offense performs away from the launching pad of Coors Field. And it’s not clear if this road-hitting handicap is fixable, or whether it will always tug down on the franchise’s chances of success.
One of the Rockies’ biggest challenges is simply making decisions based on the eye-popping numbers that get manufactured in Denver. But sabermetricians have developed ways to adjust for parks that boost or suppress scoring. According to Sean Lahman’s database, Coors Field’s park factor — a number that represents the percent change in run-scoring an average team would receive if it played all its home games at a given park — teams scored 48 percent more runs in Rockies home games from 1995 through 2001 than they would have in an average park. In 2002, a humidor was installed to make the ball less lively, and the park has toned things down since, boosting runs by 28 percent (still tops in MLB).
So even though the Rockies have allowed more runs than any other team since they came into existence, their pitching should be judged relative to their environment. It begins to look better when we account for how many extra runs anybody would have given up under the same circumstances. Judging by wins above replacement (WAR)1 — which is adjusted for park effects — Colorado’s staff has ranked in the top half of the major leagues 11 times in the 23 seasons2 since the team moved to Coors Field in 1995. And on the road, Rockies pitchers have pretty much been average since ’95 as well.
Compare that with their position players, who since 1995 have finished among MLB’s bottom five in WAR more times (six) than they’ve ranked among its top half (five). A counterintuitive narrative starts to emerge: The problem isn’t the pitchers; it’s the hitters.
At the core of the issue is this: Colorado’s hitters have scored an unbelievable 58 percent more runs per game at home than on the road since 1995, easily the biggest split in the majors. That might not be too distressing if the hitters were OK on the road and great at home. But instead they’re putrid on the road and just OK at home. Once we factor in the Coors boost, the Rockies have actually been a mediocre-hitting club at Coors since ’95 according to adjusted on-base plus slugging (OPS+), and they’ve been the very worst-hitting team in baseball on the road. They also see the biggest drop in batting effectiveness of any team in their away games.
Maybe this means Coors’ park-factor calculation is broken, thrown off by the extreme behavior of baseballs in Denver. But if so, we don’t see much evidence of it in the rest of the Rockies’ stats. A comparison between NL road teams’ total runs per game at Coors Field and at other National League parks is almost perfectly consistent with Colorado’s long-term park factor. And since 1995, newly acquired Rockies pitchers have performed at a level very close to what we’d expect from their park-adjusted track records3 before arriving in Denver. Both of these findings are in line with what we’d expect to find if Colorado’s park factor was doing its job.
More likely, the explanation is that there’s some kind of “Coors Field hangover” that leads to poor hitting performances for the Rockies when they’re away from Denver. But the big question is why — what causes the Rockies’ bats to be so ineffective at normal altitudes, even among hitters who’d been fine before donning purple-and-black uniforms?4
There aren’t a lot of great answers, although plausible theories do abound. Many have suggested that Colorado’s hitters have become so accustomed to seeing flattened-out pitches at home that they struggle to adjust against pitches that break normally on the road. However, FanGraphs’ Jeff Sullivan, writing for Fox Sports, found little evidence of that effect, at least in terms of something that wears off as a road trip goes on and batters adjust. If that is what’s going on, readjusting to normal breaking balls must require the long arc of an entire season — or multiple seasons. (Which would make sense, given the historical scale of Colorado’s road struggles.)
Another hypothesis is that opposing hurlers know certain pitches aren’t as effective at Coors, so the mix of pitches they use in Denver might be different from what the Rockies see on the road. But although recent pitch-type split data is difficult to come by, this terrific piece of research by blogger-turned-analyst Bojan Koprivica showed that, while pitches do behave differently in the thin air, the Rockies’ opponents don’t tend to change the types of pitches they throw very much in response. (Incidentally, Koprivica’s article is one of the best pitch-level investigations into the Coors Field phenomenon that you’ll read.)
One more theory supposes that a lineup built to succeed at Coors simply isn’t the type of lineup that scores runs in the average park. At home, the Rockies have focused on disciplined line-drive hitting spread over the whole field, taking advantage of the smaller range of pitch movement and higher batting average on balls in play caused by hitting at altitude. On the road, those same tactics simply haven’t worked.
Whatever the cause, the Coors Field hangover doesn’t show many signs of letting up. Even now, the Rockies are hitting for an OPS nearly 170 points higher at home than on the road (though that’s slightly narrower than the gap has historically been). Old curses die hard.
Can Eric Thames keep this up?
Alongside old favorites Mike Trout and Bryce Harper, this season’s batting leaderboard is headlined by a surprising name: Milwaukee Brewers first baseman Eric Thames. Thames, who just set a franchise record with his 11th home run this month, currently sports a ridiculous 1.393 OPS — the 18th-best April mark in history,5 and one far better than might have been expected even after he lit up Korean baseball these past few seasons. (FanGraphs’ preseason depth charts called for him to record a .838 mark.) But how have other similar hot starters (those with at least a 1.380 April OPS) finished their seasons?
|ON-BASE PLUS SLUGGING|
|YEAR||PLAYER||PROJECTED||APRIL||REST OF SEASON|
|1921||High Pockets Kelly||0.748||1.384||0.837|
Thames is near the bottom of that group, but he’s still part of a club that mostly ended up hitting very well — and exceeding expectations — over the remainder of the schedule. Not every hot April leads to an amazing May and beyond, but it wouldn’t be shocking if Thames continues to hit well this season.
Murphy mashes the Mets (again)
The NL East’s supposedly marquee Washington Nationals-New York Mets rivalry hasn’t been much of a contest recently. Washington has won 15 of 22 meetings since the beginning of last season — outscoring New York 94-57 during that span — and a lot of the blame can be cast on ex-Met Daniel Murphy.
Since leaving New York, Murphy is hitting .386 with an 1.148 OPS against his erstwhile teammates, including a grand slam in Sunday night’s nationally televised game. Going back to 1950, only one batter has killed his former team more than Murphy has been killing the Mets, according to his OPS against them:
|STATS VS. FORMER TEAM|
|RANK||YEARS||PLAYER||FORMER TEAM||PLATE APP.||OPS|
An intentional walk check-in
At the request of FiveThirtyEight political writer Harry Enten — who’s on record as hating MLB’s new intentional-walk rule almost as much as he despises the designated hitter — we’ll be periodically checking in on the state of free passes this season. Our first dispatch is a surprising one: Despite it being easier than ever to hand out a free base, intentional walks are actually down in the early going this season, dropping from 0.19 per game across MLB last year (itself an all-time low for a full season) to 0.17 thus far in 2017. Deliberate passes do tend to increase as the season goes on — presumably because in-game strategies take on more perceived importance as pennant races heat up, and because hitters have accumulated more stats with which to instill fear into opposing managers’ hearts — so it’s worth watching to see whether IBBs stay down. But for now, the instant gratification of automatically putting a man on base hasn’t resulted in more intentional walks.