The Mariners’ Bullpen Blueprint: Defining Their Profile – Part 1

They have a clear blueprint for what they want — considering pitch arsenal, ballpark fit, characteristics, velocity, and movement. In this two-part series, we will outline the traits the Mariners prioritize before moving on to potential bullpen arms who fit this criteria and could be added either before the season begins or at the trade deadline.

Mariners Pitcher Profile: The Bullpen: Part 1

Throwing Strikes

Throw strikes. This is the name of the game for Mariners pitchers. While this might sound blindingly obvious, it is not necessarily about strikeouts but about pounding the zone. Of course, the Mariners possess pitchers with elite swing-and-miss ability, but their bullpen is also full of arms whose primary goal is to induce weak contact in the zone.

The Mariners’ bullpen is filled with relievers who throw 55–60% of their pitches in the zone, comfortably above the league average, which typically sits closer to the low-50% range. There are two notable exceptions: Matt Brash and Andrés Muñoz. Those two are the strikeout arms, with some of the best bat-missing ability in the league. Even then, the group keeps walk rates below 11% and maintains sustainable strikeout-to-walk ratios. Keeping walks to a minimum is obviously key if you are looking for weak contact.

The Mariners clearly prioritize pitchers who limit free passes and force hitters to swing. While they have arms with the stuff to live outside the zone and miss bats, those are diversifiers rather than the norm. Challenging hitters have become the bread and butter of this pitching unit.

Ground Ball + Suppression Contact Quality

This kind of control limits the variables, but if these pitches are getting hit hard, pounding the zone means nothing. You need to be able to suppress the quality of contact. Seattle’s bullpen is built less on swing-and-miss volatility and more on batted-ball control.

Pitching in T-Mobile Park makes this an important quality. It is one of the hardest ballparks in the league to hit doubles and triples, and keeping the ball in the park through weak contact is vital. When you combine elite ground-ball rates with one of the toughest parks in baseball for extra-base hits, the margin for damage shrinks quickly.

As they set up for 2026, more than half of the projected group to make the final roster has a ground-ball rate above 50%. This is well above the league average, which sits around 43%. Additionally, these balls are not getting hit hard relative to league norms, with the league-average hard-hit rate around 39%. Outside of Carlos Vargas, who will be looking to bounce back from his 2025 performance, the rest of the unit sits at or below 30%.

Attack the zone and minimize quality contact, keeping the ball on the ground.

Velocity Baseline + Pitch Mix

In terms of stuff or pitch arsenal, there are certain pitch types they clearly prefer. They target pitchers with specific characteristics and have even proven willing to reshape arsenals to fit this mould. While much of the league has moved toward splitters and changeups, the Mariners have leaned heavily into sliders and sinkers.

Seattle’s bullpen profile shows a clear structural identity built around velocity, pitch concentration, and movement. What is noticeable is the absence of four-pitch arsenals with equal splits; they primarily prioritize two heavily featured pitches executed well to achieve a defined role. Each Mariners reliever features a concentrated two-pitch foundation anchored by a fastball or sinker thrown at 95+ mph.

Fastball

Nearly every reliever sits at an above-average 95 mph or higher on their fastball, with several operating in the 97–98 mph range. On top of high velocity, they primarily sit between 7–9.5 inches of induced vertical break. Four-seamers show above-average ride, designed to play at the top of the zone and lean into weak contact.

Sinkers

Sinkers are thrown with similar power, supporting a hard-contact and ground-ball suppression model. They are a key part of the arsenal for mid-relievers looking for ground balls and contact suppression rather than pure swing-and-miss. Once again, all relievers are above league-average sinker velocity.

Sliders

Sliders are heavily featured across the unit, often exceeding 40% usage, with an emphasis on horizontal movement and put-away capability. The movement profile allows them to either finish at-bats or disrupt barrels when paired with velocity. This frisbee-like movement, utilized by Brash and Eduard Bazardo, is valued but not essential. Muñoz, for example, has a much tighter slider, showing their value of distinct movement profiles. The slider is an essential weapon, and usage is organizationally heavy.

Taken together, this is not a bullpen built on deception or deep arsenals. It is built on velocity bands, concentrated pitch usage, and movement profiles designed to either miss bats or minimize the quality of contact.

The Blueprint?

The organization demands a strike-throwing baseline and either elite swing-and-miss ability or strong ground-ball and contact suppression traits. Fastballs sit 95 mph or higher, paired with heavy slider or sinker usage rather than diverse arsenals. This is the blueprint that the Mariners have built for their bullpen.

So what would a perfect Mariner relief pitcher look like?

• 97–98 mph velocity baseline

• 62% sinker usage

• 64% ground-ball rate (99th percentile)

• 4.9% walk rate (95th percentile)

• Barrel%: 4.8% (93rd percentile)

These were the 2025 stats of Jose Ferrer, traded early in the offseason. Ferrer represents the type of arm the Mariners are actively looking to acquire, and were willing to part with a top 100 prospect to get. Two-pitch mix, sinker-heavy, one of the best in the league at inducing ground balls, and rarely walks batters.

His underlying metrics put him with some of the best relievers in baseball in the exact categories the Mariners target, and Ferrer will have high expectations given that he is now pitching in a ballpark tailored to his profile.

The Mariners are not done adding relievers yet. They have been vocal about their desire to continue making bullpen additions. In Part 2, we will look to identify who else fits this mold.