The best pitch a pitcher can throw is a well-located fastball, and the Seattle Mariners subscribed to that philosophy more than any team in MLB this season.
Mariners pitchers combined to throw fastballs (four-seamers or sinkers) on 55.9% of all pitches during the regular season, the highest percentage in MLB, according to Sports Info Solutions.
Bryan Woo (72.8%) and Luis Castillo (68.2%) ranked first and second, respectively, among MLB starters in percentage of fastballs thrown, and George Kirby (55.6%) is among the league leaders.
Here are five pitches, in particular, that will define the Mariners’ playoff hopes (metrics via Baseball Savant):
1. Bryan Woo’s four-seam fastball
Usage: 47.3%
Average miles per hour: 95.7
Batting average against: .153
Weighted on-base average: .241
Strikeout rate: 31.8%
The Mariners have maintained an optimistic tone surrounding Woo’s pectoral injury, though it appears less likely that the 25-year-old right-hander will be available to pitch in either of the first two games of the ALDS at home. When — if — he does return, Woo will no doubt continue to rely on a four-seam fastball that tied for the fifth-most valuable pitch among all MLB pitches (Tarik Skubal’s changeup ranked No. 1). Woo throws his sinker 25.6% of the time, and it’s also one of the most effective pitches on the M’s staff.
2. Andrés Muñoz’s slider
Usage: 50.4%
MPH: 86.1
BAA: .109
wOBA: .156
K%: 43.8%
By virtually any measurement, Muñoz’s slider is one of the single-best pitches in MLB. One notable metric widely used among MLB teams is weighted on-base average (wOBA), which measures player’s overall offensive contribution per plate appearance. Here are the top five pitches this season based on wOBA. (For context, the league average wOBA is .313).
1. Mason Miller’s slider: .114
2. Garrett Crochet’s sweeper: .152
3. Andrés Muñoz’s slider: .156
4. Logan Gilbert’s splitter: .172
5. Tarik Skubal’s changeup: .176
3. Logan Gilbert’s splitter
Usage: 19.6%
MPH: 81.7
BAA: .119
wOBA: .160
K%: 63.8%
With two strikes, Gilbert has turned to his split-fingered fastball as his go-to, put-away pitch. Batters often know it’s coming, and they still can’t hit it. Gilbert’s splitter often dances with an unpredictable quality, much like a knuckleball, and it ranked No. 1 among all MLB pitches with a 63.8% strikeout rate this season.
4. Luis Castillo’s four-seam fastball
Usage: 46.4%
MPH: 95.0
BAA: .200
wOBA: .292
K%: 26.5%
Castillo has been brilliant in his three career postseason starts (two with Seattle in 2022), posting a 1.83 ERA with a 19-to-1 strikeout-to-walk ratio in 19 1/3 innings. He’s leaning much more on his fastballs now than he was a few years ago (32.9% four-seam usage in 2022), and it’s become his most important pitch.
5. Eduard Bazardo’s sinker
Usage: 40.6%
MPH: 95.5
BAA: .158
wOBA: .231
K%: 32.6%
Bazardo’s emergence as a trusted high-leverage arm has been one of the best storylines of the season for Seattle. He doesn’t get much swing-and-miss, but he does get a lot of weak contact with his sinker and slider. He added 1.3 mph on his sinker this year — up from 94.2 in 2024 — and it ranks as the fourth-best pitch on the M’s staff, per Baseball Savant’s run value metric.
Other notable pitches: George Kirby’s four-seam fastball, Gabe Speier’s four-seam fastball, Matt Brash’s slider, Bazardo’s slider, George Kirby’s sweeper, Carlos Vargas’ sinker.