Comerica Park might actually be a hitters' haven

Longtime Tigers outfielder Bobby Higginson once referred to Detroit's home field as "Comerica National Park," a tongue-in-cheek reference to just how large the outfield dimensions at the then-new park were. It's a good line that also holds more than a bit of truth. Thanks to a deepest-in-baseball center-field fence that's 420 feet away, Detroit has become known as an extreme pitchers' park, as the place homers go to die.
It's not hard to see where that reputation comes from, especially with the data Statcast™ has accumulated over the last three seasons. In 2017, players hit nearly 2,200 batted balls that were projected to go at least 410 feet, and as you'd expect, they were overwhelmingly hits -- nearly 99 percent of them. Only 28 of those crushed balls turned into outs. More than a third of those, 10, were in Detroit. No other park had more than four.
Due to that, Comerica is seen as a terrible place to hit. But what if it's also a great place to, well, hit?
We started thinking about this last summer when outfielder J.D. Martinez was traded to the D-backs. Going from spacious Detroit to cozy Arizona, the theory went, would boost his stats; and while he did mash with the D-backs, it wasn't about getting away from Comerica. As a Tiger in 2017, Martinez hit .336/.430/.748 (.467 wOBA) at home, but just .269/.337/.495 (.348 wOBA) on the road. It wasn't just a small-sample thing: Over his Tigers career, dating back to 2014, he'd had a .408 wOBA at home and a .363 wOBA on the road.

The same held true up and down the lineup. Before catcher Alex Avila was traded to the Cubs, he'd had a similar experience to Martinez. At Comerica in 2017, he had a .415 wOBA; on the road, it was .316. When we looked at why Miguel Cabrera had the sport's largest gap between expected outcomes and actual outcomes, we figured it would be because many high-value batted balls turned into outs in Detroit; and while that was true, it was also because he had a .351 wOBA at home and just a .277 mark on the road.
Of the 17 Tigers hitters who had at least 40 plate appearances both home and away in 2017, 13 hit better at home. Nick Castellanos had a .365 wOBA at home, and just a .315 mark away. Even light-hitting shortstop José Iglesias mashed better at home, putting up a slugging percentage of .398 in Detroit against only .338 on the road.
From a team perspective, the 2017 Tigers ranked very highly in terms of teams that simply hit better at home, nearly as high as some clubs that are considered to have extremely hitter-friendly parks.
Biggest home-field runs scored advantage, 2017
+152 Rockies
+102 D-backs
+99 Rangers
+97 Tigers
+95 A's
Biggest home-field SLG% advantage, 2017
+.108 Rockies
+.094 D-backs
+.081 Tigers
+.069 A's
+.059 Rangers
Biggest home-field wOBA advantage, 2017
+.061 Rockies
+.051 D-backs
+.048 Rangers
+.045 Tigers
+.034 Nationals

It's not just about hitters. Tigers pitchers allowed 462 runs at home in 2017, the highest number in baseball, and only 432 on the road, the seventh-most. It's not just about 2017. Over the last decade, Tigers bats have had a better wOBA at home every single year, with the cumulative difference between their .344 home mark and .319 road mark ending up as baseball's fifth-largest.

For all of the reputation as a pitchers' park, offense hasn't suffered in Detroit, other than on a few very specific deep drives to center field and the power alleys that the ballpark kept in the yard. What else is going on here?
Here's one theory: A large, dark batter's eye might just make it easier to see the ball and make hard contact with it.

"You see the ball well there," said Brandon Moss, then of the Royals, when he was asked last summer about his success at Comerica. In 22 career games in Detroit, Moss has eight homers and a .322/.375/.667 line. "It's a nice ballpark, but that's really all there is. I see the ball well there. It's got a good batter's eye."
"There isn't anything out there to distract you like some ballparks," said Avila, who spent eight of his first nine seasons with the Tigers. When he spent a year with the White Sox in 2016, he hit just .213/.359/.373 overall, but reached base six times in 14 plate appearances (including a double and a home run) as a visitor in Detroit. 
Martinez, before his own trade out of town, gave more credence to the overall home-field advantage that most athletes enjoy.
"When you're at home, you feel comfortable," he said. But he also pointed out why the road can be more difficult. "It's a different backdrop, everything's different, something you're not used to."
Back in 2015, Justin Upton, then with the Padres, told FanGraphs that "the one thing I look for in a park is whether you see the ball well." He'd soon sign with Detroit as a free agent, and in a season-and-a-half as a Tiger, he hit .276/.363/.520 (.372 wOBA) at home, as opposed to only .248/.309/.483 (.335 wOBA) on the road.

Torii Hunter got right to the point in a 2014 interview: "For me, a good park to hit in is a batter's eye that's all black. Minnesota is all black. Seattle is all black. At our park [Comerica], it's dark green and some black, so you can kind of pick up this little white ball."
In two seasons as a Tiger, Hunter had a .353 wOBA at home, and a .328 mark away.
If this is true -- if it's really easier to see the ball there -- then you'd expect it to manifest in two specific stats, aside from runs scored and slugging. You'd expect to see fewer strikeouts, and you'd expect to see more hard contact. For the most part, you do.
More contact at home
In 2017, Tigers batters struck out in 19.6 percent of their plate appearances at home, the 22nd-highest mark in baseball. On the road, that jumped to 23.1 percent, the ninth-highest. While it's true that teams do enjoy a home-field advantage -- only nine whiffed more on the road than they did at home -- the Tigers had the second-largest strikeout rate advantage, behind only the Rockies.
One year isn't enough. Let's expand it back a full 10 years. At home, only one team struck out less often than the Tigers' 17.2 percent: the notoriously contact-friendly Royals. On the road, only 11 teams struck out more than their 20.2 percent. The resulting gap was the third-largest, behind only the Rockies and Pirates.
It's the same on the pitching side. From 2008-17, a full 24 teams had a higher strikeout rate at home than the Tigers. Only three teams -- again, the Rockies, Royals and Pirates -- had more of a home strikeout disadvantage than the Tigers did.
You can see it in the numbers of the greats. Justin Verlander struck out more away from Comerica (23.1 percent) than he did at home (22.5 percent) as a Tiger. So did Max Scherzer (25.4 percent at home, 26.5 percent away). Compare that to, say, Clayton Kershaw, who has a career 29.1 percent whiff rate in Dodger Stadium, as opposed to 26.6 percent on the road.
Better contact at home
This is something we have only been able to measure in the few years of Statcast™, but it holds up. In 2017, Tigers hitters at home had a 35.7 percent hard-hit rate (balls hit with an exit velocity of 95 mph or above), the fourth-highest in baseball. On the road, that was 32.7 percent, the 11th-highest. Given the actual outcomes in terms of runs scored and slugging percentage, that shouldn't be surprising.
Detroit pitchers allowed hard-hit balls on 34.3 percent of balls in play at home, sixth-highest, and just 32.4 percent of the time on the road, 15th-highest. While Tigers batters hit harder at home, Tigers pitchers did better away.

Looking at a more complicated stat like Expected wOBA -- which attempts to ignore the effects of ballpark and defense and looks just at expected outcomes of exit velocity, launch angle, strikeouts, and walks -- it's similar. Tigers hitters at home had the highest xwOBA in 2017, at .346, and the 15th-highest on the road, at .308. Their pitchers allowed the highest xwOBA at home, and the 10th-highest on the road.
As a venue, Comerica had the highest xwOBA in baseball, and again, that's just about the moment of contact, not about outcomes. In terms of outcomes, the venue's actual wOBA was second, behind only Coors. It wouldn't be unexpected to have some minor park-to-park fluctuations in terms of measuring things like exit velocity, but obviously that wouldn't affect the actual real-world outcomes at all.
Despite all that, the pitcher-friendly reputation persists, because the deep center field does swallow up some valuable batted balls, of course, and because there's some research which suggests the wind blowing in from right-center has a serious effect. (Interestingly, the effects of the sun in Detroit are unique as well, given that no park in the game is positioned, in an east-west basis, like Comerica is.)
It's frustrating for a batter to call Comerica home, understandably. The feeling of hitting what is essentially a home run over 410 feet, just to find it becoming merely another out, must be deflating. But it's not all bad, either. In some ways, it's a fantastic place to hit.