Seattle Mariners’ bullpen has become a surprising strength

Sep 10, 2025, 2:35 PM | Updated: 2:41 pm

Seattle Sports

The Seattle Mariners’ bullpen is starting to shine at a time the team could surely use it.

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The bullpen shut down the St. Louis Cardinals over five innings Tuesday night to help secure a 5-3 victory, continuing a strong run during the club’s current four-game winning streak. The bullpen hasn’t allowed an earned run over 14 2/3 innings over the past four games, a welcomed sign after the unit had some ups and downs in August.

The bullpen was thought to be the area the Mariners fell short of fully addressing at the trade deadline, with a high-leverage arm being the potential missing piece. However, that may not be the case. Many of the numbers show Seattle’s relievers have been among MLB’s best in close games this year.

Seattle relievers have faced the 10th-most batters (1,045) in medium- and high-leverage situations this season, per FanGraphs, yet they’ve surrendered the ninth-least hits (189), sixth-least home runs (19) and fifth-least earned runs (94). The group ranks third in ERA (3.54), third in opponents’ slugging and seventh in opponents’ average (.221) in medium- and high-leverage scenarios this year.

The Four Horsemen

Much of the bullpen’s success in close games falls on the shoulders of the quartet that makes up the backend. That group includes names that were expected to produce the results they have like closer Andrés Muñoz and right-hander Matt Brash. It also features some more unexpected names like left-hander Gabe Speier and right-hander Eduard Bazardo.

All four of those arms have an ERA of 2.82 or better while pitching at least 40 innings this season. No other bullpen in MLB has four pitchers who hit both benchmarks.

The Four Horsemen is probably a fitting name for the group, because when they enter the game, the end is likely near for their opponents.

Here’s a look at what each have accomplished this season.

• Muñoz: 3-2 record, 34 saves, 1.63 ERA, 1.05 WHIP, 55 1/3 innings pitched, 71 strikeouts, 1.6 fWAR

Among relievers who have pitched at least 50 innings, Muñoz ranks second in ERA and opponents’ slugging percentage (.222), seventh in opponents’ average (.170) and 20th in strikeout rate (31.4%). He’s also third in saves, fourth in win probability added (3.43) and ninth in fWAR among all relievers.

• Brash: 1-2 record, three saves, 21 holds, 1.73 ERA, 1.13 WHIP, 41 2/3 innings pitched, 52 strikeouts, 1.1 fWAR

Brash ranks third among relievers with at least 40 innings pitched in ERA and 10th in opponents’ slugging (.267).

• Speier: 3-3 record, 21 holds, 2.82 ERA, 0.92 WHIP, 54 1/3 innings pitched, 71 strikeouts, 1.5 fWAR

Speier has the sixth-best FIP (2.32), eight-best walk rate (5.1%), 11th-best WHIP and 14th-best strikeout rate (32.9%) among relievers with at least 50 innings pitched. He’s also fifth in swing rate on pitches outside the zone (39.6%), 10th in fWAR and 10th first-pitch strike percentage (69.4%) among all relievers.

• Bazardo: 5-0 record, nine holds, 2.50 ERA, 1.00 WHIP, 72 innings pitched, 72 strikeouts, 0.3 fWAR

Bazardo has pitched the fifth-most innings out of the bullpen in MLB and has the 15th-best opponents’ average (.183) among relievers with at least 50 innings pitched. He’s also seventh among relievers with 86.3% of runners left on base.