Mariners’ Pitching Lab Lost Its Architects. Now It’s Time to Spend.
Everyone knows: the Mariners know pitching. Their “pitching lab” has been marveled at by writers, talking heads, and fans for the last several seasons. They see potential in guys that no one else sees. They turn 6th round picks into Cy Young candidates and pull high leverage relievers out of their magic hat every year. Every offseason, the recommended plan for the Mariners bullpen is to do nothing, because they can just snap their fingers once to make an elite closer appear, and twice for a setup reliever. That reputation is well-earned. The M’s were top 10 in team ERA for three straight seasons from 2022-2024, including two top three finishes.
This success is in stark contrast to where they started from. During most of the 2010s, Seattle’s pitching development was average at best. Despite having talents like Félix Hernández, Hisashi Iwakuma, and James Paxton, the team’s ERA often ranked outside the top 10, and the bullpen was a recurring weakness.
That began to change in 2016, when general manager Jerry Dipoto overhauled the organization’s player-development philosophy. He hired Andy McKay as director of player development, a pivotal move. McKay soon brought in Joel Firman, then a young analytics intern, followed by Trent Blank (coordinator of pitching strategy) and Max Weiner, a 24-year-old founder of “The Arm Farm,” who became the M’s minor-league pitching coordinator before the 2019 season. In 2021, Matt Pierpont joined as Everett’s pitching coach.
These hires were foundational for one of baseball’s best pitching pipelines. Weiner, in particular, became a rising star, praised by players and coaches alike for his preparation, communication, and ability to unlock pitcher potential. He introduced the “Dominate the Zone” mantra, helped create the “Gas Camp,” and redefined Seattle’s scouting philosophy. As pitching coach Pete Woodworth later said, “When Max came in, it was a big shift — we started drafting and acquiring different types of players, with traits we knew would work.”
The success stories poured in. The list of pitchers they’ve developed or revived is remarkable:
Andrés Muñoz: acquired while rehabbing Tommy John surgery; became a dominant closer.
Matt Brash: traded for while still in A-ball.
Bryan Woo: a sixth-rounder in 2021 with a 6.49 college ERA turned big-league breakout.
Bryce Miller: fourth-round pick from the same 2021 class.
Paul Sewald: failed Mets reliever reinvented by throwing high fastballs and sliders with more sweep.
Gabe Speier: waiver pickup who thrived by adjusting pitch useage.
Eduard Bazardo: DFA’d by Baltimore in 2023, acquired for a minor prospect, and reshaped into a key arm.
The M’s have done this for years — unearthing gems like Penn Murfee, Justin Topa, and Erik Swanson seemingly out of thin air. Joel Firman pushed hard for Bryan Woo in the 2021 draft. Harsh grader Trent Blank gave Woo his first and only 80-grade scouting evaluation ever. Their process was validated multiple times by Mariners pitchers, including Paul Sewald, who publicly stated that his career turned around 180 degrees after coming to Seattle, and credited the Mariners player development and analytics as the reason for the changes that made him so successful.
The Mariners’ success drew league-wide attention. Other teams wanted a piece of their “secret sauce.” One by one, key members of the dev ops staff are being poached.
Max Weiner left for Texas A&M in 2023 to become their head pitching coach.
Matt Pierpont, his assistant and successor, was hired by the St. Louis Cardinals as director of pitching after the 2024 season.
Losing both the minor-league pitching coordinator and his right-hand man in consecutive years was a major blow. The organization still has talent in the building, with Andy McKay, Trent Blank, and Joel Firman remaining with the team. Mckay is now the assistant GM and Vice president of Baseball operations. Trent Blank served a dual role as both coordinator of pitching strategy and bullpen coach for a bit and is now the director of pitching strategy for the entire M’s organization. Matt Pierpont quickly made his way up the ranks and was promoted to assistant minor league pitching coordinator by 2023. Joel Firman worked his way up to assistant GM along with McKay. But the loss of Weiner and Pierpont removed the two of the most hands-on architects of Seattle’s pitching magic.
There haven’t been as many transformation stories in the last couple of years, and certainly not from guys acquired after Weiner’s departure. 2025 was the first season since Pierpont left, so the full impact of that loss hasn’t been felt yet. But we can already see signs of change.
Let’s take a look at the bullpen from 2021-2023 and compare it to 2024-2025.
2021 BP: 618 innings pitched, 3.88 ERA (8th in MLB), 3.72 FIP, 1.22 WHIP, 6.8 fWAR. The six relievers with the most innings were: Paul Sewald, Drew Steckenrider, Casey Sadler, Anthony Misiewicz, Rafael Montero, and Will Vest. Steckenrider, Sewald, and Sadler had all been given up on by their previous teams, and the M’s were able to acquire them for nearly nothing and quickly turned them into a formidable trio.
2022 BP: 544 innings pitched, 3.33 ERA (6th in MLB), 3.11 FIP, 1.08 WHIP, 3.8 fWAR.
The six relievers with the most innings were: Penn Murfee, Andres Munoz, Paul Sewald, Diego Castillo, Matt Festa, and Erik Swanson. Castillo was the only pitcher in that group who was an established reliever before being acquired by the Mariners. All the other guys were success stories of the pitching dev ops.
2023 BP: 548 innings pitched, 3.48 ERA (4th in MLB), 3.80 FIP, 1.26 WHIP, 5.3 fWAR. The six guys with the most innings were: Matt Brash, Justin Topa, Gabe Speier, Andres Munoz, Tayler Saucedo, and Paul Sewald. None of them were established relievers before joining the Mariners organization.
2024 BP: 490 innings pitched, 3.71 ERA (9th in MLB), 3.91 FIP, 1.17 WHIP, 1.5 fWAR. The six relievers with the most innings were: Trent Thornton, Austin Voth, Andres Munoz, Collin Snider, Ryne Stanek, and Tayler Saucedo. Notably, Matt Brash missed the whole season and Sewald had been traded in the offseason, but this was still a huge step back. This was the first time in recent years that they hadn’t been able to compensate for bullpen losses and guys having down seasons. For the first time in a while, their ‘flip’ candidates, Austin Voth and Ryne Stanek, didn’t pan out (they combined for 0.0 fWAR over 100 innings pitched).
2025 BP: 580 IP, 3.72 ERA (9th in MLB), 4.04 FIP, 1.28 WHIP, 3.2 fWAR. The six relievers with the most innings were: Eduard Bazardo, Carlos Vargas, Andres Munoz, Gabe Speier, Casey Legumina, and Matt Brash. Once again, none of their ‘flip’ candidates worked out. Vargas and Legumina pitched a lot of innings but were worth a combined -0.7 fWAR. Although Bazardo finally took a step forward, he wasn’t a post-Weiner and Pierpont acquisition. And that’s really the most important thing. They haven’t brought in anyone that panned out lately. In fact, two of the guys they gave up on flipping, Drew Pomeranz and Luke Weaver, had breakout seasons this year. Outside of the established guys they have already had for a while, only one guy did anything positive.
Relievers are notoriously unpredictable, which is exactly why the Mariners’ development success was so valuable. But that reliability was a product of the people behind it, and two very important guys are gone. Even the best systems cannot instantly replace that expertise. And that’s not to say that the Mariners aren’t going to be good at developing pitching. They were still able to get Bazardo to take a huge step forward, even though it took a while (he was acquired in 2023). Their top starting pitching prospects are doing well; there is no reason to believe that they aren’t still a very good team when it comes to finding and developing relievers. But it is clear to me that the miracles they used to perform are not going to happen as frequently anymore. And whether you believe the losses of Weiner and Pierpont have had a big impact or not, the fact remains that you cannot bank on flipping relievers when you’re trying to win a World Series.
The bullpen was astonishingly terrible outside of Brash, Munoz, Bazardo, and Speier this season. If you remove their WAR from the total, the M’s Bullpen was worth -1.7 fWAR. That means that if the back end of the bullpen had just been average (0.0 fWAR), they would have had 4.9 fWAR as a unit. That is a high number, and it could be hit just by adding one more elite reliever. The M’s should have the finances to make something happen, considering the situation. Jerry Dipoto has gone on record saying that he expects the payroll for next year will start at the same level they ended the 2025 season with, which is around $160-165 million. Some estimates have the Mariners’ current obligations as low as $132 million after arbitration, so the front office could have upwards of $30 million to work with this offseason. With a strong reliever free agent class that includes Edwin Diaz, Robert Suarez, Devin Williams, and Tyler Rodgers, this offseason is an excellent opportunity to reinforce the bullpen with a proven commodity.
2025-2026 Relief Pitcher Free Agents
Final Thoughts
With more payroll flexibility and ownership recognizing that the contending window is open, Seattle should be willing to invest in at least one high-leverage reliever. They just need one more guy they can trust in those situations, so they don’t feel the need to use a worn-out Bazardo in game 7 of the ALCS (sorry, too soon). Seattle has earned its reputation for pitching wizardry. Now it is time to acknowledge that even magic can’t last forever. Just as they bolstered the rotation with Luis Castillo and Robbie Ray, they must do the same with the bullpen. Spending money on a reliable reliever this offseason is not a risky move; it is a necessary one.
-Isaac harai
