1 big reason Mariners could be legit October threat

August 28th, 2022

When you think back to recent examples of teams that rode dominant bullpens to World Series titles, the 2015 Royals, 2013 Red Sox and last year’s Braves are probably among the first teams that come to mind.

The 2022 Mariners could join that list … if they manage to get to the postseason.

That’s a big if, of course, considering Seattle is in the midst of the longest playoff drought in the four major North American professional sports. The club hasn’t reached the postseason since 2001, when Ichiro Suzuki was a 27-year-old rookie. Ichiro, now 48, was inducted into the Mariners Hall of Fame on Saturday.

So, yeah, it’s been a long time since we saw the M’s in the playoffs.

But they have a good chance to end the drought this year. Entering Saturday, the Mariners were 2 1/2 games ahead of the Orioles, five games ahead of the Twins and six ahead of the White Sox in the race for the third American League Wild Card spot. Seattle is also in the mix for a higher Wild Card seed, with the Rays just a half-game ahead and Blue Jays percentage points ahead. The M’s playoff odds, per FanGraphs, were 93.4% after Friday’s win over the Guardians.

The Mariners’ relief corps has played a huge part in the team’s success this season. Seattle leads MLB with 28 one-run wins, three more than any other team. Those one-run victories make up more than 40% of the team’s total wins.

In terms of expected wOBA allowed, which is based on quality of contact (taking into account exit velocity and launch angle), strikeouts and walks, the Mariners’ bullpen leads the AL at .280 and is second in MLB behind the Dodgers (.278).

Merely reaching the postseason will be cause for celebration among Mariners fans everywhere, but the team has a real chance to make some noise in the playoffs thanks to its bullpen.

Here’s why Seattle’s ‘pen is a unit no team is going to be happy to face come October. (Stats below are through Friday.)

They have one of MLB’s most dominant arms

In his seven years at the helm, Mariners president of baseball operations Jerry Dipoto has earned a reputation as one of MLB’s most aggressive decision-makers, shaping the team's rebuild with a long list of trades. It didn't seem like much at the time, but Dipoto made one of his most important deals during the shortened 2020 season, sending catcher and relievers and to the Padres for a four-player package that included infielder , who has become an All-Star in Seattle.

Also part of that deal? Right-hander Andrés Muñoz, who was recovering from Tommy John surgery when Seattle acquired him. Muñoz returned to the Majors on the final day of the regular season last year before making Seattle’s 2022 Opening Day roster.

After a slow start, the 23-year-old has been nearly untouchable during the summer, recording a 0.59 ERA, a 0.19 FIP and a .324 opponents’ OPS over his past 28 games.

Consider these Muñoz numbers:

  • He averages 100.1 mph with his four-seam fastball, second highest in MLB.
  • He has a 41.8% whiff rate, third highest in MLB (min. 100 swings).
  • He has a 42.1% strikeout rate, third highest in MLB (min. 100 batters faced).
  • He's tied for third in xBA (.156), ranks fourth in xSLG (.241) and ranks second in xERA (1.76) among 365 qualifying pitchers.

Given his velocity, it wouldn’t be surprising if Muñoz’s four-seam fastball was his primary pitch, but that actually isn’t the case. In fact, Muñoz has thrown his four-seamer 38.4% of the time this year, compared to a 61.6% usage rate with his slider.

Opposing hitters have gone 14-for-116 (.121) with 64 strikeouts against Muñoz’s slider in 2022, and his 52.1% whiff rate on sliders is the third-highest mark any pitcher has posted with any individual pitch type (min. 200 swings on the pitch type).

Highest whiff rate on individual pitch type, 2022
Min. 200 swings on that pitch type

  1. Edwin Díaz (NYM), slider: 54.4%
  2. Spencer Strider (ATL), slider: 52.2%
  3. Andrés Muñoz (SEA), slider: 52.1%
  4. Corbin Burnes (MIL), curveball: 48.8%
  5. Max Scherzer (NYM), slider: 48%

They go seven deep on pitchers who can miss bats

When the stakes are highest, having relievers who can come out of the bullpen and get strikeouts is incredibly valuable. The Mariners, who rank fourth in the big leagues in reliever K-rate (26.6%), have a bevy of these arms.

Including Muñoz, Seattle has six pitchers who have a strikeout rate of 25% or higher, have faced at least 150 batters and have made at least half of their appearances in relief:

The Mariners are the only team with as many as six such pitchers (according to Stathead), while two other teams have five, seven have four and the rest have three or fewer.

That doesn’t even count , who has a 24.4% strikeout rate this season but has posted a 0.91 ERA and a 28.2% K-rate in his past 30 games. While none of the six pitchers above has appeared in the postseason, Castillo registered a 1.08 ERA and a 29% K-rate over 14 playoff appearances for the Rays in 2019-20, so his experience could prove vital come October.

They throw a ton of sliders

How Seattle’s bullpen is achieving its success may be as important as the actual results when projecting how it will fare in the playoffs. While Muñoz, Brash and Castillo all throw hard, this isn’t a ‘pen built around velocity. Rather, the M’s relief corps is heavily reliant on sliders.

Collectively, Mariners relievers have a 41.4% slider usage rate, not only the highest this season but also the highest for any bullpen in the pitch-tracking era (since 2008). A whopping 58.7% of the bullpen’s strikeouts have come on sliders, also a high in the pitch-tracking era.

Here’s a breakdown of the average slider velocity, vertical drop and horizontal break for each of the seven key Seattle relievers:

  • Castillo’s slider: 88.3 mph, 28.9 inches vertical, 0.3 inches horizontal
  • Muñoz’s slider: 88 mph, 29.9 inches vertical, 4.7 inches horizontal
  • Brash’s slider: 86 mph, 37.8 inches vertical, 15.4 inches horizontal
  • Swanson’s slider: 84.8 mph, 31.7 inches vertical, 6.4 inches horizontal
  • Festa’s slider: 82.8 mph, 37.4 inches vertical, 15.9 inches horizontal
  • Sewald’s slider: 82.7 mph, 31.7 inches vertical, 12 inches horizontal
  • Murfee’s slider: 79.7 mph, 40.7 inches vertical, 17.1 inches horizontal

If you’re a hitter, you might be able to get a bead on someone’s heater if you see them several times in a short series, but figuring out a bunch of wicked sliders with different velocities and shapes is a much tougher task.

They should be fresh

As good as the Mariners’ bullpen has been this season, it hasn’t been overworked.

Seattle’s starting rotation, which is led by reigning Cy Young Award winner/offseason addition and was augmented by a Trade Deadline deal for , has thrown the fifth-most innings in MLB. Meanwhile, the Mariners rank 26th in reliever innings.

The team also has limited the frequency of multi-inning relief appearances, tying for last in the number of appearances in which a reliever pitched in more than one inning and ranking 29th in bullpen appearances totaling more than three outs.

As a result, Seattle's relievers should have plenty left in the tank for the stretch run and postseason.

The addition of Castillo will also give the club the opportunity to get creative with its bullpen in the playoffs. Seattle could roll out a postseason rotation of Ray, Castillo, and , in some order, and move rookie righty to the 'pen. Or keep Kirby as a starter and use Gilbert in relief. Either way, the relief corps would gain another potential difference-maker.

The Mariners may not seem like a legitimate contender, with the 23rd-highest runs-scored total in the AL and a good-but-not-great starting staff that ranks 18th in FIP. But Seattle's bullpen has the makings of a special unit that could fuel a deep October run.