Every team heads into spring training with The Plan for their roster. February is a time to dream about what could be, as new offseason acquisitions mix with the holdovers in camp. Then the reality of March settles in, spring injuries start to mount and The Plan is suddenly compromised or needs to be thrown completely out the window. For the Mariners, The Plan for their bullpen included some combination of Andrés Muñoz, Matt Brash, and Gregory Santos locking down the final few innings of any game they were leading. Unfortunately, the latter two of those three relievers are now dealing with injury issues that will keep them from being ready come Opening Day.

Brash had been dealing with elbow inflammation this spring after making more appearances (78) than any other reliever in baseball last year. Thankfully, surgery isn’t on the table yet, but the M’s are taking an understandably cautious approach to a key member of their ‘pen. Santos ended last season on the injured list due to an elbow issue and showed up in Arizona this spring with a sore shoulder. He had just started to ramp up his throwing program when he strained his lat on Tuesday. It doesn’t appear to be a serious issue, but it’s another setback for a pitcher who appeared to be a key offseason acquisition. In addition to losing Brash and Santos to start the season, Seattle’s bullpen depth took a hit when Jackson Kowar was diagnosed with a UCL tear last week; he will undergo Tommy John surgery, sidelining him until 2025.

To provide some insurance for their sudden lack of high-leverage options, Seattle signed Ryne Stanek to a one-year, $4 million deal on Friday. A setup man for the Astros over the last three years, Stanek compiled a solid 2.90 ERA during that time, though his 3.91 FIP wasn’t as pretty thanks to a very high walk rate. Still, his 27% strikeout rate and elite stuff allow him to be effective despite all the traffic on the basepaths.

Last year, Stanek managed to get his walk rate to a hair below 10%, the lowest of his career. His strikeout rate also dipped, however, and the extreme home run luck he enjoyed in 2022 regressed back towards his career norms. The end result was an ERA over four and a FIP more than a run and a half higher than it was two years ago. The improved walk rate is pretty easy to dissect: Stanek located his pitches in the strike zone at the highest rate of his career last season. Specifically, his fastball was thrown over the plate almost 60% of the time. Opposing batters weren’t fooled by the change in approach; hitters’ overall swing rate against Stanek’s pitches rose five points to a career-high, an increase that was entirely driven by additional swings on pitches in the zone.

The desire to curtail his problem with free passes is a noble one, though pumping fastballs into the strike zone might be the wrong strategy. Stanek doesn’t have great command of his slider or splitter, though both of those pitches generate tons of swings and misses. For as good as his secondary offerings are, Stanek is pretty reliant on his four-seamer, throwing it nearly 65% of the time. Perhaps the Mariners’ vaunted pitching development lab can help him figure out how to hone the command of his secondary offerings. For his part, Stanek is excited to work with the team to find ways to improve. “As a pitcher and somebody that wants to get better, it’s a really cool thing to watch and now to be a part of,” he told reporters after signing. Even if nothing changes, he’ll still be an experienced high-leverage reliever filling a sudden gap in Seattle’s bullpen.

With Stanek now in the fold, it appears as though the Mariners have six spots in their relief corps nailed down, with Muñoz, Gabe Speier, Tayler Saucedo, Trent Thornton, and Austin Voth rounding out the group. That means there are two spots up for grabs and plenty of pitchers battling to break camp on the major league roster:

Carlos Vargas was one of the players the Mariners acquired in the Eugenio Suárez deal this offseason, and his raw stuff gives him a leg up on the rest of the competition. His fastball sits in the upper 90s and he also possesses an excellent hard slider. His outings this spring have been a little inconsistent, but if he’s able to harness his command with the help of the Mariners development staff, he could be a real weapon out of the ‘pen. He’ll likely get a shot to prove he can stick in the majors out of spring training.

The final spot is more up in the air. With both Brash and Santos likely to return from the IL sometime early in the season, roster flexibility will be paramount. That means non-roster invitees and players who don’t have any minor league options remaining have extra hurdles to overcome. That includes Ty Buttrey and Tyson Miller, two spring standouts. The former is attempting to return to the majors for the first time since 2020; he stepped away from baseball in 2021 and has spent the last two years toiling away in the minor leagues. At his peak back in 2019, however, Buttrey was a high-leverage reliever for the Angels and is reportedly firing fastballs in the upper 90s this spring.

Miller has drawn comparisons to Paul Sewald from Mariners manager Scott Servais this spring thanks to his riding fastball, sweeping slider, and low release point. And like Sewald, Miller is a bit of a reclamation project after having bounced around between three different teams last year:

If you squint, you can kind of see some similarities between Sewald and Miller. Miller’s release point is low, though not as low as Sewald’s, and his fastball has some pretty good ride to it, though not as much as Sewald’s. What Miller does have working for him is elite extension down the mound thanks to his 6-foot-5 frame.

Buttrey and Miller will need to continue to stand out through the end of the month to secure that final spot in the Mariners’ bullpen. It’s much more likely Seattle will go with one of the options already on their 40-man roster, like Cody Bolton or Mauricio Llovera. Both were offseason waiver claims and neither has had much success in the majors so far. Bolton has a mid-90s fastball that he pairs with a sweeper and a changeup. Like Stanek, he fills the zone with his heater and attempts to get batters to chase his secondary stuff out of the zone, though that approach didn’t work in the big leagues during his brief cup of coffee last year. Llovera has a little more major league experience, seeing action in parts of the last three seasons. He works east-to-west with a sinker-slider arsenal that has tons of horizontal movement. He’s also out of minor league options, making his fight to make the Opening Day roster a little more urgent.

No matter who they go with, though, they’ll need to get creative with how they deploy their bridge relievers to get to Stanek and Muñoz in the eighth and ninth innings. What’s really exciting is thinking about the potential strength of this unit once Brash and Santos return to full health. As Servais put it, “We have a lot of velocity. And if we get everybody healthy, we have a shit ton of velocity.” Until then, the Mariners will have to hope that Stanek and whoever emerges from their spring competition will be enough to hold down the fort.

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