T-Mobile Park is the hardest place in MLB to hit again - especially if you hit it perfectly

In 2022, the Seattle Mariners played their 24th season at T-Mobile Park, née Safeco Field. It was one of the club’s most successful campaigns ever, but it was also another triumph for the park itself in re-establishing its reputation as one of the premier pitcher’s parks in Major League Baseball. In the dead of winter here still, awaiting the warm embrace of Spring Training, I am curious if there is a particular culprit for this offensive backslide by all players when they set foot in the Magenta Center. I’m also inclined to think the park plays at least some role in Seattle’s efforts (or lack thereof) to lure quality free agent hitters to Seattle. And I suspect the club has recognized these same issues, and recognized that the “three true outcome” style hitters who walk, strikeout, or homer most frequently will ultimately have more success than most at their current home field.

By the park factors of Baseball Savant using Statcast data, T-Mobile Park was, for the second-straight season, the most difficult park to hit in in all of MLB. Other sites, like ESPN, also keep park factor data; however, Savant’s shows a bit more depth in analyzing the parks themselves, whereas ESPN simply compares runs scored by a team on the road vs. at home (T-Mobile Park ranks 28th). The chart below (and the link) will show you that same Statcast data from Baseball Savant in greater detail, and a few points stand out.

Baseball Savant

T-Mobile Park is in the cellar overall as an offensive environment, a full nine percent more offense-suppressing than a league-average park and a whole 20% tougher to hit in than Great American Ball Park in Cincinnati, the second-most hitter-friendly confines in the league behind elevation-aided Coors Field which will reign supreme in perpetuity until MLB expands to Bogotá or Mexico City. But despite its obvious low-offense layout, as has been the case since the team moved in the fences in left and center field prior to the 2013 season (outside of 2013 itself), the park has actually been a perfectly reasonable environment for hitting home runs. T-Mobile Park actually ranked a tick ABOVE-average in terms of home runs in 2022, marine layer be damned. However, in every other category, it was a nightmare to try and make hay at the plate, as Seattle’s home field was one of the hardest places to land hits of any kind in the field of play, and in particular it was the hardest place to triple in all of MLB.

The lesson? If you want to score in Seattle, it seems, you’ve got to put the ball over the fence, because any lesser contact is destined for less success here than anywhere else.

If we expand the data to the a three-year rolling sample from 2020-2022, it shows the same conclusion for T-Mobile Park: 30th out of 30, and even more dramatically so.

Baseball Savant

The three-year sample is best practice for evaluating this sort of effect as it provides a sample size of 16-17,000 plate appearances and helps shake out some impacts from any extreme individual hitter or season. However, there is one important data point for 2022 in particular. In 2022, every MLB club and ballpark was required to use a humidor to store baseballs prior to use for the first time, in an effort to better standardize playing environments to some degree. At parks in drier climates, the humidor should have a moistening effect, reducing the flight distance of the ball on contact. In wetter (or more water-rich air-having) areas like Seattle, the impact could actually in theory have been an increase in flight distance, particularly given the balls were set to be stored at 70 degrees Farenheit and 55% relative humidity league-wide. But T-Mobile Park has had a humidor for longer than most of MLB, having installed one prior to the 2020 season.

And at least by some metrics, this seems to have helped - at least relative to the rest of the league. Though Seattle as usual was the coldest park on average for games, and its sea level atmosphere did it no favors, the humidor appears to have improved the ability of balls to fly by an average of over two feet from 2019 (pre-humidor) to 2022, moving T-Mobile Park from 30th in extra ball flight distance to merely 24th. Of course, in T-Mobile’s case, this is still an average LOSS of ball flight distance of about 4.3 feet on average, though down from 6.4 feet in 2019. And all of this is compared to “league-average,” which has been far from static.

Back in 2018, our Jake Mailhot looked at how a seemingly deadened baseball was helping the Seattle Mariners’ pitching staff have greater success after a rabbit ball in 2017 had been devastating to their fly-ball inclined pitching staff. Then in 2019, things got juicy again, so much so that the league began making secret (and eventually were exposed publicly to have made) efforts to alter the ball to reduce home runs. While research by Dr. Meredeth Wills and Insider’s Bradford William Davis found there were secretly three types of baseballs used in 2022, the overall deadening impact was most prevalent. Below we can see the impact on fly balls at T-Mobile Park, and how dramatic the overall impact has in fact been of this medley of factors.

Baseball Savant

Over that same time span, MLB league-wide has seen serious fluctuations in fly ball distances as well; however, T-Mobile Park has been right about in line with most of the rises and falls.

Baseball Savant

So T-Mobile Park has seen changes roughly in line with the rest of MLB due to alterations to the ball, and the improvements to ball flight from the humidor have not been sufficient to counteract the temperature and other environmental factors to bring it up close to league average. Over the past three years, T-Mobile Park has hosted a run environment a staggering 17% lower than league-average, 5% worse than the next lowest in San Diego and nearly equivalent to a run-preventing shadow version of Coors, GABP, or Fenway Park. Park factors are accounted for in stats like wRC+/OPS+/DRC+ and ERA+/FIP-/DRA- (they’re what the +/- indicate), but to frame how much lower scoring games are likely to be at T-Mobile Park than at a league-average park, it is the gap between Cal Raleigh (121 wRC+) and J.P. Crawford (104) wRC+.

And where specifically are these offensive gaps coming from? As shown in the charts above, home runs are still reasonably common compared to the rest of the league in T-Mobile Park, something reflected in its 17th-ranked wOBA on fly balls (excluding pop-ups) (.417), albeit with a .104 BABIP (24th) that reaffirms what we’ve alluded to: if it doesn’t get over the fence, it’s almost always landing in a glove. There’s no major variability in ground ball outcomes in Seattle, as is to be expected given less variability in field surfaces and T-Mobile Park’s extremely streamlined field dimensions, leading to a 13th-ranked wOBA (.219) and BABIP (.237) on grounders (.219). Pop-ups are almost guaranteed outs everywhere, which leaves us with the holy grail of contact: line drives. What you’re encouraged to hit every level of baseball from T-ball to the bigs worked worse at T-Mobile Park than anywhere else in 2022.

Obviously line drives are still quality contact here as they are everywhere, but not as resoundingly as you’d expect. In fact, a fly ball in Boston was more likely to be a hit than a liner in Seattle. That’s obviously Green Monster-aided, but some combination of the environmental factors, the now-undersized outfield, and the relatively firm and shallow outfield walls in straight right and left field seem to render T-Mobile Park a tricky place to find outfield grass. So while 250 foot lasers like this still can find purchase, albeit for singles easily corralled by quickly pinching outfielders...

...249 foot darts like this can be quickly stopped up or snagged despite what would be an easy single or even double elsewhere:

In essence, T-Mobile Park has become the opposite of Coors Field in its totality. A small outfield relative to much of the league in terms of total possible real estate, at sea level, in a cool and wet environment that suppresses the ball’s flight further, all conspire to reward boom or bust hitting. That’s in direct opposition to Coors’ palatial outfield expanses, designed to hopefully curtail the massive home run potential but in exchange allowing doubles and triples to bloom in the warm summers of Denver’s thin, dry mountain air, encouraging hitters to simply set the bat to the ball and let things fall as they may.

So to review, we’ve got a last-place park for runs and general offense, where triples and extra-base hits are an extreme rarity relative to the rest of the league. Specifically, while ground balls and fly balls turn out about as well as average for MLB in T-Mobile Park, the best type of contact - line drives - fares far worse in Seattle than anywhere else, both from a standpoint of turning into extra-base hits and even turning into hits at all. Seattle has built a roster relatively successfully around that fact, with a pitching staff that had the highest fly ball rate in MLB last year and one of the lowest walk rates, letting contact in play largely putter out. It is, in essence, a triumph of the “Control the Zone” philosophy, that by reducing free passes and affording hitters more opportunities for contact early in the count and either forcing them to strike out or put the ball in play, the pitcher will ultimately benefit most.

It’s likely that this plays at least some role in Seattle’s troubles enticing free agent bats to the Puget Sound, though money talks and the M’s have been astoundingly mum all winter. Conversely, the club should be able to continue luring pitchers to their shores, if they so desire. It’s also important to consider for their current roster, and a good reason players like Eugenio Suárez and Cal Raleigh are well-suited to loft moonshots to success, whereas contact-heavy hitters with more line drives in their contact profile, while still obviously well-suited for success overall, may not be as successful as expected in Seattle. I’m not sure exactly how to parse this, or whether the M’s should even be encouraging their hitters to do anything different, as line drives are still the best contact in terms of a positive result, but for players like Ty France and Julio Rodríguez who have both the power to loft homers and the bat control to make plenty of contact, more loft means more runs produced. Conversely, this continues to insulate players like Marco Gonzales and Chris Flexen, who can get by on even plentiful contact that might sink them at other parks. Next year, the M’s should run out an exciting roster that can contend for the playoffs once again. Just remember how their home park impacts their numbers when you consider their play.