When you stare into the batter’s eye in Seattle, something unfamiliar stares back.
What a batter sees at T-Mobile Park changes within a game and season.
Last year, I tested batter vision at T-Mobile Parking using the position of the sun. My premise was that if there is an issue with vision, we should see performance change as light changes in the stadium. I found the sun to be a strong predictor of performance overall and discovered a spike in whiff rate just after sunset. I concluded some batters likely struggle to see at T-Mobile Park.
But lots of things change with the sun. As the sun sets, temperatures drop, air density rises, and wind patterns change. Mike Petriello explained in January how some of these variables contribute to T-Mobile Park’s extreme whiff environment. While the backdrop likely matters, it’s not the only reason offense is limited in Seattle.
Still, for decades the batter’s eye at T-Mobile Park has been a curiosity, a scapegoat, and a symbol of futility. Today, I want to share some new data about the backdrop itself, and discuss how it could change what a batter sees in Seattle.
The data
I found every batted ball to center field in 2024 at T-Mobile Park using the video archive at Baseball Savant. I captured a screen shot from the center of the batter’s eye for each play. I loaded the images into R and wrote a function using magick to extract pixel data. I then measured the average pixel brightness for each image and matched it up with the sun.
The following plot shows pixel brightness from the batter’s eye as the sun sets from right to left. Day games are the cluster on the right, night games are the cluster on the left, and the dashed-vertical line is sunset.
In night games, the color of the batter’s eye changes as you would expect. It’s brightest when the sun is above the stadium, and it gets slowly darker as the sun sets throughout the evening. Once the sun drops below the horizon, the color is stable. The batter’s eye is much brighter on clear nights than it is on cloudy nights. When the roof is closed, the color of the batter’s eye is always dark.
In day games, the data is less obvious. The batter’s eye is actually much darker during the day and doesn’t change much over the course of a game. This makes sense, given the sun starts in center field and moves clockwise around the stadium, meaning there isn’t much direct light on the batter’s eye until the evening. It’s somewhat surprising cloudy days appear brighter than clear days, although it’s possible clouds help direct light back toward the batter’s eye.
This data confirms my initial premise: the stadium looks different as the sun changes position throughout the day and year. Unfortunately, there isn’t much direct application beyond that. The sample is small, and the quality is low — i.e., we can’t simply measure performance against the color data. That said, I do think we can use this information with the sun model to walk through a few theories.
Glare
Glare isn’t the main issue at T-Mobile Park, or at least not the one that makes it unique. I can’t say it doesn’t exist, but I don’t find a difference in performance between bright/clear days and dark/cloudy days when the sun is above the stadium. Any glare at T-Mobile Park is likely brief, rare, and not more substantial than other venues.
Glare was the original vision complaint from batters in the early days of the stadium. Dan Wilson, for instance, told The Seattle Times in 2002 that the glare coming off the batter’s eye “can be so brilliant it is blinding.” The team made a variety of changes to the structure of the batter’s eye and eventually settled on the much darker material it is now in 2004.
For a point of comparison, I followed the same process with the center field fence. The fence is a lighter/brighter color than the batter’s eye, and it appears much brighter in the summer when the sun hangs above the rim of the stadium to the west.
Given the old batter’s eye was a similar forest green, there’s a good chance the full backdrop was much brighter 20 years ago. Glare might have mattered then, even if I don’t see evidence of it now.
Color
That “whiffs go up as the sun goes down” is why I landed on the color of the batter’s eye as the culprit in my last post. The surface installed in 2004 was designed to prevent glare. It’s been described as “very, very, very black.” It’s engineered with light absorbing honeycomb material, meant to take the light that hits it, hold onto as much of it as possible, and minimize what’s reflected toward the batter. It’s quite good at doing so.
The batter’s eye doesn’t just *seem* dark — it is indeed the darkest batter’s eye in MLB. I ran an abbreviated analysis on the batter’s eye at every stadium in MLB. It’s not an apples-to-apples comparison for a few reasons, but I did find the batter’s eye at T-Mobile Park to be sufficiently unique in color. For example, here it is compared to the brightest batter’s eye at Fenway Park.
Why would this matter? Well, here’s how Wikipedia describes the effect of Vantablack, a material with light-absorbing properties similar to the honeycomb surface:
When applied to three-dimensional objects, Vantablack produces the appearance of a two-dimensional surface or void space.
The batter’s eye is not truly Vantablack, so the comparison may not work. But something about it doesn’t feel quite natural. As 2015’s top viral image reminds us, extreme color can make it difficult to see things as they are. And I’ve come across enough “stare at this image for 10 seconds and the color will change” illusions to believe this could matter. That said, I did not find darker always meant worse within T-Mobile Park, nor did I find darker backdrops across the league were always associated with more strikeouts. I’m not sure the color of the batter’s eye is an issue (and it seems to help with the glare), but it’s another unique element of the stadium nonetheless.
Angle
The batter’s eye is (notoriously) set at an angle, from right field out toward left. Edgar raised suspicion of the angle in 2004, and it’s been a talking point ever since. I’ve personally been skeptical of this theory for a while, as I can’t visualize why this would matter, having never stepped in the box myself. And as Petriello points out, T-Mobile Park isn’t unique in having an angled batter’s eye. Both Camden Yards in Baltimore and Progressive Field in Cleveland have a similarly angled batter’s eye. We don’t suspect anything of them.
But maybe we should. Rob Gray at Perception Action points out there’s some plausible science going on here. An angled backdrop could create a “texture gradient” and change a batter’s sense of visual depth.
As a surface gets further away from us, the texture elements on it … get closer together. This is why “the grass is always greener on the other side of the fence” – blades of grass (texture) are perceptually more tightly packed on your neighbor’s lawn because it is further away than yours – so you don’t see all the imperfections in between!
In other words, a batter may misperceive location, movement and velocity when looking against an angled backdrop, which would affect swing decisions, timing, and contact.
Gray goes on to say batters should quickly adjust to the angle using the visual information in the space beyond the batter’s eye. And that’s what makes this next chart somewhat notable. I ran my sunset model over all 30 parks. Most stadiums showed more whiffs after sunset. Comerica Park showed the largest increase, although it had the fewest pitches after sunset by far. The next largest changes in whiff rate were at Camden Yards, Progressive Field, and T-Mobile Park. Each stadium with an angled batter’s eye showed a stark change in performance at the moment depth-correcting visual information disappeared into the night. Batters whiffed more when they could no longer “see” the angle.
The placement on this list is more convenient than explicitly damning. Almost half the stadiums exist within a few decimals of each other, and the narrative disappears when arranging the data in different ways. I’ve also found it’s not quite so simple to turn “vision” into a leaderboard like this. Stadiums are amorphous, and they change at sunset for a variety of reasons not always linked to their backdrop. But if there’s an issue with the structure of the batter’s eye, I now lean towards the angle.
Golden (sombrero) hour
When a batter steps to the plate at T-Mobile Park, they see something new.
Seattle is MLB’s northernmost city, which means it has the longest sunsets, especially in the summer. This implies there’s more variation in how the stadium looks each time a batter steps to the plate. While most stadiums change with the sun, none experience longer shifts in color than T-Mobile Park. The plot below shows how long it takes the sun to set in Mariners home games versus road games. The sun sets 30 minutes later on average at T-Mobile Park, and this difference can be closer to an hour around the summer solstice. Batters rarely get the same look twice.
This could compound any issue with the physical structure of the batter’s eye. Gray points out batters should eventually pick up on the visual trick created by the angle, so long as the distortion is constant. But as the chart above shows, it’s not.
This change in perceived slant makes it difficult to re-calibrate to any changes in the perceived ball trajectory. The required adjustment is likely changing from at-bat to at-bat. It’s virtually impossible to adapt to a distortion that is non-constant.
A shifting backdrop could reduce or eliminate the small advantage batters gain on a pitcher throughout a game. Stephen Sutton-Brown at Baseball Prospectus, in his research on pitch arsenals, found batters adapt to pitchers the more they see them.
It’s hard to condense what makes the great hitters great into a set of individual skills. Strength, coordination, and sharp vision are important, but [familiarity] skill reveals something beyond a good set of eyes and intuition. To improve with familiarity a batter must, in a fraction of a second, not only absorb the new information and integrate it with what he’s already seen that day, but also organize his body to adjust to that information mid-swing.
If batters get familiar with what they’re seeing from a pitcher, it’s possible they get familiar with what they’re seeing beyond a pitcher as well. The structure of the batter’s eye makes that difficult, and Seattle’s ever changing backdrop even more so.
With that in mind, let’s look at the whiff environment on clear days versus cloudy days:
On clear nights, when the “look” of the stadium changes the most, we see more whiffs than expected. On cloudy nights, when the stadium provides a more consistent backdrop, we see more even performance. Sunset itself represents the largest change in backdrop during a game. It comes earlier or later depending on the month and the start time, but on average, it’s around the fifth inning. This is a crucial moment in the “familiarity” game, when starting pitchers either work through the order for the third time, and batters expect to gain an advantage; or pre-leverage relievers enter the game, and batters make their first adjustment. Perhaps the new backdrop disrupts that balance.
We see whiff rate about one point higher on clear evening games in the sunset hours. This setting makes up about 15% of pitches thrown at T-Mobile Park. It’s an effect both large enough to measure and small enough to not look too concerning. I think the batter’s eye matters to some batters a lot and to others not at all.
Teoscar Hernández has commented on what he saw at T-Mobile Park three times over the last year. He’s clearly thought about it. Here’s his latest quote:
“When you step in the batter’s box, you try to see the pitcher straight. For me, I couldn’t figure that out. I always see myself crooked. It’s either the pitcher was behind me, or on the other side of the mound. It was never straight, like the other stadiums.”
I don’t know what he saw, but he wasn’t comfortable. Teo swung and missed on 22% of pitches he saw on clear nights in Seattle. No batter over the last four years whiffed more in that setting.
The batter’s eye
The batter’s eye at T-Mobile Park is unique. It’s an uber-light absorbing material at the center of a small, dark backdrop, angled in a way that distorts visual depth. Its structure could make it difficult for batters to adjust to what they’re seeing, and Seattle’s nature demands they adjust often. In a game of comfort and repetition, batters rarely see the same thing twice.