A quick review of Park Factors readily available at sites like ESPN and Statcast reinforces a truth long known to Seattle Mariners fans. T-Mobile Park is a pitcher-friendly venue. Just for fun, I decided to search for rotation trade candidates capable of benefitting from the Mariners’ home field advantage.

And what advantage am I referring to, specifically? 

Baseballs don’t fly as far in Seattle.

The T-Mobile Effect

It’s true. Over the past five seasons, fly balls hit in the ballpark at the corner of Edgar & Dave have averaged the shortest distance travelled of any MLB venue.

Shortest Average Fly Ball Distance (in feet)
T-Mobile Park (Mariners) – 314
loanDepot park (Marlins) – 314
Oracle Park (Giants) – 314
Citi Field (Mets) – 315
Dodger Stadium (Dodgers) – 316
Oakland Coliseum (Athletics) – 316
Citizens Bank Park (Phillies) – 316

The “T-Mobile Effect” isn’t a new concept. Others have written about. But it’s an important dynamic that shouldn’t be overlooked, even during an era where putting the ball in the air is a popular strategy with hitters. To see what I mean, let’s compare the Mariners’ home and away stats on fly balls in 2021.

M's Fly Ball Success At Home and Away
HR/FB%
AVG
OBP
SLG
wOBA
Dist
Home
14.5
.222
.218
.713
.371
309
Away
15.7
.285
.276
.874
.456
319
MLB
17.1
.281
.274
.877
.457
318

In Seattle, the hometown nine’s staff produced significantly better results than the MLB averages included on the preceding table. Yet, the same group was essentially league-average when toeing the mound away from T-Mobile Park.

Considering the Mariners’ staff collectively performed so well on fly balls at home, it’s reasonable to believe starters with above average fly ball rates may benefit from calling T-Mobile Park home. For proof of this theory, look no further than an unexpectedly good Seattle acquisition from last offseason – Chris Flexen.

Straight Outta Korea

By now, Mariners fans are familiar with Flexen’s back story. A 14th round pick of the Mets in 2012 given few major-league opportunities before New York released him in 2019. A year later, the 27-year-old reinvented himself with the Doosan Bears of the Korean Baseball Organization before becoming Seattle’s best starter in 2021.

While Flexen finally enjoyed MLB success as a Mariner, opposing hitters were noticeably more productive against the righty when he wasn’t pitching at T-Mobile Park. Particularly in the power department.

Chris Flexen's 2021 Home/Away Splits
FB Out%
ERA
HR%
AVG
wOBA
FB Dist
Overall
79.5
3.61
2.6
.268
.311
316
Home
84.7
3.23
1.8
.257
.289
307
Away
73.7
4.06
3.5
.281
.335
326
MLB
72
4.27
3.3
.244
.314
318

As you can see, Flexen had good overall numbers and was decent on the road. But he was special at home. Perhaps not so coincidentally, fly balls didn’t travel as far and were converted into outs more often at T-Mobile Park compared to everywhere else the Californian competed this year. 

Discovering and signing Flexen to a multi-year deal proved to be a coup for Mariners President of Baseball Operations Jerry Dipoto and his staff. Perhaps Dipoto and crew could find a similar starter on the trade market capable of using the team’s park factors to his benefit. Let’s consider four potential candidates.

Help Wanted

The first name on our list is someone Mariners fans have seen on a regular basis since 2019. I’ve suggested in the past that he’s an underrated performer. That’s not the case anymore.

Chris Bassitt, RH – Athletics

FB Out%
ERA
HR%
AVG
wOBA
FB Dist
Overall
84.3
3.15
2.4
.218
.274
300
Home
91.1
2.44
2.2
.196
.239
292
Away
80
3.71
2.5
.235
.299
306
MLB
72
4.27
3.3
.244
.314
318

The 32-year-old was superb regardless of location this year with a 3.15 ERA that was 19th best among starters. Still, he’d be a perfect fit for T-Mobile Park.

Bassitt’s 91% fly ball out rate at the Oakland Coliseum was the best recorded at home by any starter this season. Moreover, his 9.2% HR/FB rate was sixth lowest within the same group. And who was ranked just ahead of him at fifth? Chris Flexen.

Fun fact: At 299 feet, 2021 NL Cy Young Award winner Corbin Burnes was the only starter with a lower average fly ball distance than Chris Bassitt (300).

Most baseball observers believe the low-revenue A’s will shed payroll this offseason. Especially after the team allowed three-time Manager of the Year Bob Melvin to sign with the Padres. If Oakland actually goes into sell-mode, trading Bassitt will likely be a priority considering he’ll be a free agent after next season.


Tyler Mahle, RH – Reds

FB Out%
ERA
HR%
AVG
wOBA
Dist
Overall
67.8
3.75
3.2
.234
.308
308
Home
56.6
5.63
5.4
.270
.364
327
Away
76.9
2.30
1.2
.204
.259
293
72
4.27
3.3
.244
.314
318

Mahle was excellent in 2021, although the 27-year-old could potentially deliver even better numbers if his home games weren’t in Cincinnati.

At Great American Ballpark, Mahle’s 56.6% out rate on fly balls was the worst in the majors. Yet, his 76.9% out rate on the road was 17th best. It’s conceivable that the Newport Beach, California native could be a star at T-Mobile Park.

With the Reds also reportedly looking to trim their budget, Mahle has been the subject of trade speculation. Cincinnati’s seventh round pick in the 2013 MLB June Amateur Draft is entering his second year of arbitration-eligibility and will be a free agent after the 2023 season.


Zac Gallen, RH – Diamondbacks

FB Out%
ERA
HR%
AVG
wOBA
Dist
Overall
78.8
.430
3.6
.233
.313
323
Home
73.2
4.06
4.4
.237
.314
341
Away
84.1
4.55
2.8
.230
.312
307
72
4.27
3.3
.244
.314
318

Several of Gallen’s home/road splits look relatively stable, although the ball did travel further and produce more damage when he was pitching in the desert.

The New Jersey native’s 21.1% home run/fly ball rate at Chase Field was the sixth highest home park rate in the majors. Conversely, his substantially better 11.1% rate away from Phoenix was top-30. That’s essentially the same as top free agent starter Kevin Gausman (11.2%) and 2021 AL MVP Shohei Ohtani (11.3%).

Gallen is the youngest candidate on our list and also has the most club control remaining. For these reasons, the Diamondbacks may not be interested in moving the North Carolina alum. Especially after the club recently hired long-time Astros pitching coach Brent Strom to fill the same position with Arizona.


Nick Pivetta, RH – Red Sox

FB Out%
ERA
HR%
AVG
wOBA
Dist
Overall
71.3
4.53
3.6
.234
.316
317
Home
62.1
5.40
5.3
.261
.357
325
Away
81
3.75
2.1
.208
.277
309
72
4.27
3.3
.244
.314
318

Pivetta intrigues me the most. Not only did the 28-year-old have extreme home/away splits, he’s originally from Victoria, Canada. So, there’s a Pacific Northwest connection, which would make his acquisition even more fun.

Sentimentality aside, there’s no denying that Fenway Park isn’t a welcoming place for fly ball pitchers. Since the beginning of the 2019 season, hitters have an MLB-leading .545 wOBA on fly balls at the historic yard. Coors Field was second highest at .531. Knowing all that, it should surprise no one that Pivetta’s home numbers were suboptimal.

Pivetta is arbitration-eligible for the first time this offseason and potentially a free agent after the 2024 season. Whether the Red Sox would entertain moving a starting pitcher with so much club control remaining is unclear. Especially after the team just lost free agent starter Eduardo Rodríguez to Detroit.

Assuming the Sawx were amenable to trading Pivetta, he’d be a prime candidate to reinforce Seattle’s rotation.


A Few Other Good Men

Although our focus was on trade candidates, there are several free agents capable of using the T-Mobile Effect to their advantage – Gausman, Max Scherzer, Rich Hill, and Kwang Hyun Kim. Anthony DeSclafani was originally on my list until he re-signed with the Giants.

Oh, and let’s not forget former Mariner Tyler Anderson.

Anderson was a stabilizing force for the Mariners’ rotation after coming on board in late-July. The southpaw enjoyed an impressive 80% fly ball out rate at T-Mobile Park compared to a below-average 68.4% rate at every other ballpark he pitched in this year. Perhaps the Mariners and Anderson eventually conclude that the 31-year-old remaining in Seattle makes sense.

Finally

It’s important to remember that surrendering fly balls at T-Mobile Park doesn’t necessarily guarantee positive outcomes. For example, visitors had a 1.000 SLG against Yusei Kikuchi this year. That’s better than his 1.271 SLG on the road, but both numbers were awful. 

That said, I do believe the potential does exist for the Mariners to find a few pearls capable of flourishing in Seattle due to their fly ball success.

Just ask Chris Flexen. 

My Oh My…

Got a take on what you just read? Talk about it here!

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Luke Arkins

Luke is a native New Yorker, who grew up as a Mets fan. After the US Navy moved him to the Pacific Northwest in 2009, he decided to make Seattle his home. In 2014, Luke joined the Prospect Insider team. During baseball season, he can often be found observing the local team at T-Mobile Park. You can follow Luke on Twitter @luke_arkins

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