Does Coors Field Make Rockies’ Batters Worse on the Road? by Eno Sarris July 9, 2015 Denver is where pitchers’ peripheral numbers go to die. Humidors and huge outfields have mitigated the issue a bit, but that’s still the first thing that comes to mind for most stat heads when the words “Coors Field” are uttered: Oh, those poor, poor pitchers. There’s evidence, though, that the ballpark messes with hitters, too. Rockies hitters have the biggest home/road splits in baseball over the past five years … even after you correct for park effect. By weighted runs created plus, they’re 17 percent worse on the road than at home, whereas the league average home and away split is 10 percentage points lower. In other words, Coors Field seems to giveth at home and taketh away on the road. When I asked Rockies hitters about this and checked the numbers, a clearer picture emerged: The Rockies are pitched differently at home, and their response to that difference seems to lead to problems on the road. All along, we thought pitchers were the only ones negatively affected by playing half their games at Coors Field; turns out, hitters are affected, too. Let’s get to the root of what’s happening. First, we’ll look at how things are different at home, then explain how it’s affecting the Rockies’ performance on the road (at least those not named Nolan Arenado, who actually has more home runs and a higher OPS on the road this season). Rockies hitters are pitched to differently at Coors than on the road Rockies second baseman DJ LeMahieu sums it up pretty well. “Pitchers are more confident on the road than they are in our park,” LeMahieu told me before a recent game. He explained that this added level of confidence leads to more off-speed stuff on the road. Outfielder Charlie Blackmon was even more specific. “At home, guys throw more fastballs, and the ball seems to get on you quicker,” Blackmon said. This has been an ongoing theme for years. Former Rockies pitcher Jhoulys Chacin once told me that he shelved his curveball when he pitched at home because “it’s hard to throw a curveball at home.” Dan Rozenson at Baseball Prospectus explains this by showing that the curve has less movement at high altitude. The data backs what these players are saying: The Rockies do see more fastballs at home, especially four-seamers (the hardest, straightest fastball). FanGraphs writer and researcher Jonah Pemstein found that away-team pitchers throw four-seam pitchers 41 percent of the time at Coors Field, the highest percentage of any park in baseball. Across baseball, pitchers throw four-seamers 35 percent of the time, on average. These added four-seamers come mostly at the expense of sinkers, curves and changeups — all pitches that depend on movement to be effective. So the Rockies see the straightest stuff at home. The “hometown adjustment” As a result of seeing more fastballs at home, the players tend to alter their strategy. “Since guys are less likely to throw spinning pitches in Coors, I make sure to cover the fastball when I’m at home,” said Blackmon. The Rockies swing at about the same number of fastballs at home versus away, but they have much higher contact rates at Coors. They have swung at 49 percent of the four-seamers they’ve seen on the road this year, and 48 percent of those they see at home. But they’ve made contact on 76 percent of the four-seamers they’ve seen on the road compared to 83 percent at home. In terms of outcomes, they’re a full run above average on fastballs at home, and a run below average on fastballs on the road. For the league, contact rates are higher and swing rates are lower at home, but the difference isn’t anywhere near as drastic as it is for the Rockies. The league swings at four-seamers a tiny bit more on the road (47.0 percent to 46.9 percent) and makes a little more contact at home (75.6 percent to 74.6 percent), but both numbers are much less extreme than the effect the Rockies see. Combined pitchers throwing more fastballs, this has a large effect on offense in Coors. This year, 36.6 percent of balls put in play by Rockies hitters at Coors were fastballs, whereas only 28.8 percent of balls in play by Rockies hitters at away parks were fastballs. Hitting approaches So how do we link these facts — the Rockies see more fastballs at home and put more of them in play — to create a story that explains why the Rockies are so bad on the road offensively? Let’s turn to something LeMahieu added when discussing his approach at home versus on the road: “Hitting is hard enough as it is, so to change your approach based on the park, that’s pretty tough.” If you had a decision between these two strategies, which would you choose: Strategy 1; An approach that works very well for 81 home games plus a handful of road games, but not well for the remainder of the games. Strategy 2: An approach that would be passable at home but hold up better in most road games. Most would take the guaranteed 81-plus-game approach, and it seems most Rockies hitters would as well. The cause and effect The Rockies see more fastballs at home and have adjusted their approach to swing at more fastballs; they swing at fastballs 4 percent more than the league average at home. And they succeed, boasting an .841 OPS against fastballs at home, a full 48 points higher than the league average (.793). Against “soft stuff” (slider, changeup, curveball, splitter), the difference is actually more pronounced — .773 OPS at home versus the .623 league average — because they can rely on off-speed pitches not having the same bite they do at lower altitudes. On the road, Rockies hitters still go after those fastballs, swinging at 4 percent more of them than the league average, and swinging at soft stuff 10 percent less than the league average. The problem: They see 4 percent fewer fastballs compared to home games, and don’t have near the same success (.724 OPS, 30 points below the league average). They actually hold their own against soft stuff (right around the league average), though their contact rates are below the league average. All told, here’s what the table looks like: Clearly they rock at home; no secret there. But all those added fastballs at home have made the Rockies more aggressive as a whole. And when they go on the road, that aggression serves them poorly. What can be done? Well, they could be less aggressive on fastballs on the road, though as LeMahieu noted, that’s easier said than done. Rockies hitters definitely have it good at home; Coors Field is a dream park for a hitter. But Rockies hitters also have the most adjustment to make when they hit the road, and it takes a special hitter to constantly flip that switch back and forth and succeed in all venues. By that standard, only three players on this year’s team qualify as special hitters: Arenado, Blackmon and Troy Tulowitzki, who hits much better at home but is still quite adept on the road. (Carlos Gonzalez has similar home and road splits this season, but he hasn’t been great in either split and his OPS was 401 points higher at home than on the road in 2014.) Just three hitters. With odds like that, the ol’ Rox will have a tough time climbing out of last place. Thanks to Jonah Pemstein for help with the data.