For the most part, home-field advantage in baseball doesn't matter as much as it does in other sports. To wit: Home teams in 2017 won just under 54 percent of their games. Meanwhile, since 2000, NFL home teams have won about 57 percent of the time and NBA squads have played .600 ball at home. In 2007, MLB home teams won 54 percent of the time, same as it was in 1997, 1977 and 1947. Let's agree, then, that any generic home team should be considered a 54/46 favorite.
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But baseball is very different in the dry air of Chase Field, and it's very different in the high altitude of Coors Field, to the point that the D-backs and Rockies play in what are probably the most extreme home parks in the game. Thanks to the natural forces at work in their stadiums, no teams are helped as much at home as these two, and, at least in the case of the Rockies, no one is hurt as much on the road. That Wednesday's National League Wild Card Game landed in Phoenix and not Denver means this showdown pretty much has the largest potential swing in home-field advantage of any possible matchup.
Let's start with this: The D-backs won 64 percent of their home games, second in baseball to the Dodgers. The Rockies won 57 percent, a top-10 mark. Each went 41-40 on the road.
And this, too: Over the last five seasons, the Rockies have won 18 of their 48 games at Chase Field -- 37 percent -- which is tied with the Braves for the lowest success rate of any NL opponent there.
Part of the reason for such success is because both the D-backs and Rockies were absolute sluggers at home. If we look at every team's home hitting performance using wOBA (think of it like regular OBP except it gives credit for extra base hits rather than treating all times on base equally and it is not park-adjusted, with 2017's league average wOBA being .326), we will see that the Rockies and D-backs are first and second in all of baseball, by a lot.
But on the road, we'll see that they're 23rd and 24th. The differences between home and road performances are the largest in baseball. Put another way: At home, they hit like Corey Seager; on the road, they hit like Ronald Torreyes.
It trickles down into the individual numbers, too. Just look at some of the biggest names on each club and ask yourself if you were the opposition, which version of this player would you rather see?
Take Colorado's Charlie Blackmon, who hit .391/.465/.775 (.503 wOBA) at home and .276/.337/.447 (.332 wOBA) on the road -- basically the difference between "2003 Barry Bonds" and "2017 Josh Harrison" -- and imagine how happy Zack Greinke is to be facing a leading NL MVP Award candidate in Arizona rather than at Coors Field. (For what it's worth, Blackmon hit just .182/.200/.273 in Arizona this year, and .265/.293/.442 in 44 career games there.)
Or ask Greinke how he feels about Mark Reynolds wearing road grays (.242/.311/.392, .305 wOBA) instead of home whites (.294/.393/.584, .409 wOBA), or the same for the road version of Carlos Gonzalez (.203/.274/.332, .263 wOBA) as opposed to the still-dangerous Denver version (.323/.403/.520, .390 wOBA).
Remember, though, this isn't just about Coors Field, because Chase Field has a similar effect for hitters. There's a reason, after all, that next season the D-backs will become the second team -- after the Rockies, of course -- to install a humidor, which one study by respected physics professor Dr. Alan Nathan suggested could reduce the number of home runs by 25 percent or more.
There's no humidor yet, though, so on Wednesday, the D-backs get the J.D. Martinez who mashed a .373/.448/.891 (.536 wOBA) home line with Arizona, as compared to .242/.292/.617 (.365 wOBA) away. Instead of being on the road sending up a pretty good Paul Goldschmidt (.277/.365/.493, .360 wOBA), they get the absolute monster version (.321/.443/.639, .442 wOBA). They'll start the Brandon Drury who looked like an All-Star (.302/.369/.528, .379 wOBA) at home, as opposed to the Drury who hit like a pitcher (.232/.261/.368, .267 wOBA) on the road.
Certainly, you could find examples of other players who have such splits on other clubs, but nothing quite this drastic. Drury, in Arizona, hit like Gonzalez in Denver. Gonzalez, on the road, hit like Alcides Escobar. It matters, a lot.
But we have to be fair here, especially to the Rockies. Yes, playing at Coors Field helps your batting line considerably. The effects of altitude make the air thinner, which makes pitches move less and batted balls go farther, and the enormous outfield meant to reign in home runs means that Coors Field routinely is near the top of the league in hits allowed. Blackmon had a league-leading 14 triples this year, as many or more than three teams; 13 came at home. His NL-best .331 average makes for the fourth time in five years, and 10th in 20 years, that a Rockie has won the batting title.
It's easier to hit at Coors and harder to pitch there. It's also a lot more complicated than that, because there's evidence that Rockies hitters aren't just helped by Coors Field at home, they're hurt by it on the road, too. It's what we call the "Coors Field effect."
As we've explained in the past, you can easily see this by looking at simple runs scored totals for the Rockies over the last decade. From 2007-16, the Rockies scored by far the most runs at home, topping Boston by 265. In the same period, they scored by far the fewest runs on the road, finishing 198 runs the behind 29th-best Astros. In order for that to happen, either Coors Field must be so powerful that it could elevate baseball's worst offense to look like its best, or, far more reasonably, they've had a decent offense that has been both elevated at home and hindered on the road.
There's many theories behind why, though the most plausible seems to be that the Rockies see more fastballs and fewer good curveballs at home. That's backed up by the fact that in that same 2007-16 time span, the Rockies struck out a league-high 22.3 percent of the time on the road, but just 17.5 percent, or sixth-fewest, at home. We're not even to contact or batted-ball distances yet, and there's a measurable effect.
It's not that the Rockies can't win on the road, of course; they did win five games in Arizona this year. It's just that their home park makes their hitters look better in Denver and worse everywhere else. They're facing a D-backs team that overperforms at home, too, except only one side has the home-field advantage on their side in a one-game playoff. It's not everything, not with ace Jon Gray, who has twice whiffed 10 D-backs hitters at Chase Field starts this year, on the hill. It's just maybe more than it usually would be.