The change that would help Mariners’ bats? Pushing the fences back

During the final game of the Seattle Mariners’ 2024 season, the conversation on the radio broadcast turned to the team’s troublesome offense.

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That was to be expected. The M’s knew at that point that they would be missing the playoffs for a second straight season, and there was no bigger reason for that than Seattle ranking in the bottom third in MLB in runs scored.

What Mariners broadcaster Aaron Goldsmith focused on, however, didn’t have to do with runs, or the team’s MLB-high strikeout total, or a need to hit more homers.

“It’s interesting, one of the Mariners’ offensive issues for a while now has been doubles. They just do not hit many doubles at all,” Goldsmith said. “The Mariners have been at the very bottom in terms of overall doubles for years now at this point.”

It was an astute point by Goldsmith. The Mariners finished with just 228 doubles in 2024, worse than all but three other teams in baseball, and marking the third time out of the last four seasons that Seattle ranked in the bottom six of MLB in doubles. In each of those three years, Seattle finished in the bottom three in doubles hit at home, including twice where the Mariners were dead last.

“We’ve talked to some people who study these kinds of things – park effects – and there is a strong belief that the gaps, the alleyways in right-center and left-center here at T-Mobile, just eat doubles alive,” Goldsmith continued. “… (The belief is) the ball kind of hangs here just long enough, more than other ballparks on average, and that keeps those fly balls up and allows an outfielder to cover some ground and make the catch.”

The thing is, those fly balls hanging up don’t just limit doubles at T-Mobile Park. They limit all base hits at T-Mobile Park.

Welcome to the problem with the Mariners’ offense.

And they can fix it – if they want to.

Let’s talk about T-Mobile Park

The Seattle Mariners’ home ballpark has never been friendly to offenses.

This was known pretty much from Day 1 when the team busted out of the cozy Kingdome into the unforgiving sea air at what is now known as T-Mobile Park. And sure, there have been years when it’s been a little easier to hit at the corner of Edgar and Dave, but it’s seemingly only gotten worse over time.

We all know the first answer to increasing offense is getting the right players, so no need to argue about that point. That doesn’t change the fact that Seattle’s park is unquestionably the hardest on hitters in all of baseball.

T-Mobile Park being the toughest on hitters isn’t just an opinion. It’s a fact, as the stadium ranks dead last in MLB in Statcast’s Park Factor whether you’re looking at a three-year rolling average or just the 2024 season.

Park factor is decribed by MLB.com as “a great way of determining the extent to which a stadium favors hitters or pitchers. It isn’t affected by the teams or players involved, because those teams and players are also playing games in other stadiums. It simply compares how easy it is to score, from one ballpark to another.” The statistic uses the number 100 as league average, and T-Mobile Park scores a 91 when you combine 2022-24 – which is five points below the next lowest (Tampa Bay at 96) – and an 89 when looking at just 2024 (next lowest is the Cubs’ Wrigley Field at 91).

That 89 park factor this year marked the first time that any team’s home ballpark ranked lower than a 90 since 2012, when T-Mobile Park was an 86 (more on that later). The last time any other team’s park ranked that low? You have to go all the way back to 2009 when San Diego’s Petco Park scored an 89.

What makes T-Mobile Park’s park factor so low? Statcast has all sorts of park-related rankings that can help explain, most of which the Mariners’ home scores low (we’re gonna stick with the three-year average for these).

Strikeouts? There’s no place it happens more frequently, which is why you may be aware of calls for the batter’s eye beyond the wall in center field to be changed.

Base hits? No place where they happen less.

Doubles? Same.

Triples? They occur 41% less frequently in Seattle than the league average.

Home runs?

Well, actually, that’s almost close to normal. It’s a 96, which means it’s just 4% less than league average, ranking 19th out of the 30 ballparks. The reason? The Mariners redid the dimensions of T-Mobile Park back in 2013, bringing in the fences throughout the playing field.

In left field, the wall was brought in anywhere from 4 to 17 feet closer than before. Straight center to the right-center gap came in 4 feet. And the height of the wall throughout the outfield was made uniform at 8 feet tall, removing one feature where it was previously 16 feet in left. So clearly, this change did have its intended effect – home runs went up in Seattle. In fact, in the first eight years after the fences came in, T-Mobile Park averaged nearly 3% more home runs than league average, including a whopping 121 home run factor in 2016. But in the four years since that eight-year span, T-Mobile Park has averaged over 3% less home runs than league average.

So what changed in the last four years? Baseball. Well, the baseball. After 2019 saw a league-record 6,776 homers hit, MLB introduced a new ball in 2021 that an independent lab found would “fly one to two feet shorter on balls hit over 375 feet,” according to the Associated Press. That’s surely had an impact in Seattle, where the lack of flight has shown up not just in the home run category but in the general ability to land a base hit, especially the gaps where the walls are 378 feet in left-center and 381 feet in right-center. So when the ball’s flying one to two feet shorter on average on balls hit over 375 feet, you can see why T-Mobile Park might be tough for hitters in the gaps.

OK, but is there a solution? Maybe. Now let’s take a trip to Kansas City.

As Mike Petriello broke down in a recent MLB.com article, Kansas City’s spacious Kauffman Stadium is surprisingly a hitter’s haven despite having baseball’s second highest overall field square footage (T-Mobile Park is 25th, per this chart). As a whole, Kauffman Stadium’s park factor is 104, ranking fourth in MLB. But it ranks 27th in baseball with an 85 score in home run factor.

So you’re saying more home runs don’t necessarily equal more offense? Bingo.

And you probably know what I’m getting at now. Those fences? It’s time to push them back to where they were before, if not even further.

Not enough room

When the fences were brought in at T-Mobile Park, yeah, it made it easier to get a few more balls over the wall. But it decreased the amount of area that outfielders have to cover on defense. And in the colder months in Seattle when the marine layer is present, it’s an especially easy ballpark to track down deep flies. When you combine that cold marine air with the current makeup of MLB’s baseballs, fly balls just don’t fly as well as pretty much any other place in the league. They’re gonna hang up, and when the dimensions don’t require the outfielders to cover all that much ground, those deep flies to the gaps are gonna get caught.

Just ask Jesse Winker. Or Kolten Wong. Or Mitch Garver.

Or, really, the Mariners’ pitchers. Yeah, there’s a reason the M’s have put so many of their eggs in that basket in recent years.

If you really want the point hammered home that T-Mobile Park isn’t as big as it should be, look at the BABIP numbers. BABIP stands for batting average on balls in play, and over the last three years, T-Mobile Park’s BABIP is just .273. That’s second-to-last in MLB, with only New York’s famously bandbox-y Yankee Stadium lower (.271). Six parks have BABIPs over .300, including Kauffman Stadium (.305).

Now, I don’t know if the Mariners necessarily want to fix this. They’ve smartly built around their pitching staff, and president of baseball operations Jerry Dipoto spoke at the end of the season about trying to bring in hitters that fit the ballpark perhaps more than they do the offensive philosophies the team has championed in recent years. But I think there’s a reason they should want to fix it.

A “park effect” on Seattle Mariners’ roster

Have you ever wondered why hitters rarely seem to land with the Mariners in free agency? Well, you should consider all this information and then put yourself in the shoes of an available position player. If you’re a superstar hitter with designs on making the Hall of Fame or seeing your name on season leaderboards, would you sign a multi-year contract to play for the team whose stadium is the most likely in the league to suppress your numbers? Or if you’re a free agent in your late 20s to mid 30s, don’t you think the stories of how Seattle’s park played for hitters like Winker, Wong or Adam Frazier might tip the scales toward a different team?

Maybe the Mariners should attempt to drastically overpay hitters in free agency in order to get them here, though I’m not sure that alone would solve a fundamental issue. Just like it’s completely fair to wonder if the Mariners are paying enough to compete, it’s fair to wonder what role their ballpark may play in big bats avoiding Seattle. When you see All-Stars like Winker, Jorge Polanco and Teoscar Hernández perform below their career norms after being acquired by the M’s in trades, it’s easy to see why recent free agents who may have been in the team’s sights (for example Marcus Semien or Trevor Story) have gone elsewhere.

MLB Network insider Jon Morosi spoke about this on a recent edition of Seattle Sports’ Wyman and Bob while discussing a potential free agent target for the Mariners.

“The bigger obstacle here is that we have seen a lot of players who have gone to Seattle – Mitch Garver being a recent example as a free agent – and not have great years,” Morosi said. “Now is it they’re putting too much pressure on themselves? Do they not like the hitting backdrop? There’s any number of different theories here in terms of why that is… but the reality is the perception is there. And what happened with whether it was Garver or Polanco (in 2024) didn’t exactly help that situation.”

So because of the Mariners’ ballpark constraints, they’re probably always going to have work smarter in this aspect. And that’s why pushing the fences back should be a consideration, just like finding players whose skill sets won’t be squashed by the doubles-eating gaps of T-Mobile Park should be, or adjusting the batter’s eye that has garnered attention periodically through the years.

The M’s have a great pitching staff and one of the speedier outfields in the game with Randy Arozarena in left, Julio Rodríguez in center and Victor Robles in right, so the extra space that pushing the fences back would provide shouldn’t drastically impact the home-field advantage Seattle’s pitchers have against opposing offenses. And if the Mariners start prioritizing contact hitters with speed over some of the more all-or-nothing power hitters they’ve cycled through in recent years, it will probably play even better with more room to work with in the outfield. To succeed as a hitter is to hit it where they ain’t, so why not add more places where they ain’t? (A quick aside: Do you think Ichiro would have had as many hits as he did if the T-Mobile Park fences had already been brought in when his career started? Yeah, he probably would have found a way to keep his numbers up, but if ever there was a hitter and a ballpark made for each other…)

The Mariners have run into a wall the past two seasons. They’re a good team with an elite starting rotation but not enough offense to make them truly great. Everything needs to be on the table to help get those pitchers into the playoffs, where they could do some serious damage in October. Personally, I’d start with the fences.

More on Seattle Mariners offseason

• Mariners Free Agency: Why Christian Walker is the 1B Seattle should pursue
• Mariners starting pitcher among MLB’s early arbitration qualifiers
• Cal Raleigh becomes Mariners’ first Platinum Glove winner
• Which notable former Mariners are free agents this offseason?
• Keith Law on Seattle Mariners: A big free agent and trade partner who fit

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