It’s important not to lose sight of how the Seattle Mariners are, in fact, having a good season. It was barely more than a week ago that they capped off a run of nine straight series victories. And even after a subsequent cooldown, they remain in first place in the AL West at 24-19.
Still, it’s time we all came together to cross our arms, bow our heads, and begrudingly admit that we’re all worried about the very thing that was supposed to be the Mariners’ set-it-and-forget-it strength in 2025: the pitching.
Whereas the Mariners co-led MLB with a 3.49 ERA in 2024, their 3.96 ERA for 2025 ranks only 14th out of MLB’s 30 clubs. There is some fluky stuff going on — i.e., a 37-point increase on batting average on balls in play — but there are also three statistical explanations for the downfall.
The Mariners’ 1st Major Issue: Strikeouts (or lack thereof)
If it feels like the Mariners are giving us fewer chances to write “K” in our scorebooks, it’s because that is just plain true. The team’s strikeout rate is down 3.1 percentage points relative to 2024, the largest drop in all of MLB.
The Mariners are like every other team in that they’re getting squeezed by a smaller strike zone. This has taken away one of the key advantages that M’s hurlers got from pitching to Cal Raleigh, whose framing helped result in an unusually high (i.e., fifth in MLB) rate of called strikes outside the zone in 2024.
Broadly speaking, though, Mariners pitchers just haven’t been as nasty. The club’s average fastball is down 0.8 mph from last year, and it’s behind only the Baltimore Orioles with a 2.3 percent drop in its overall whiff rate.
It’s the bullpen that is really letting the Mariners down on this front. Seattle relievers are only fanning batters at a 20.8 percent clip, the second-lowest in the American League after the Kansas City Royals. If it wasn’t for Andrés Muñoz and his 35.6 K%, things would obviously be worse.
The Mariners’ 2nd Major Issue: Way too many walks
The Mariners didn’t mess around with free passes last year, as their 369 walks were the fewest of any team by a whopping 47 over the Minnesota Twins. They gifted the opposition no more baserunners than they absolutely had to.
Though basically only a quarter of the season is in the books, the Mariners are already 40 percent of the way to last year’s walk total with 145 so far in 2025. The shrinking strike zone is once again a factor, but there has also been a surprising lack of execution by the starters.
The rotation has nearly doubled its walk rate, going from 4.9 percent in 2024 to 8.4 percent in 2025. Their actual rate of pitches in the zone has declined only modestly, yet their rate of three-ball counts is up almost a full percentage point from 7.2 to 7.9. You just can’t decrease your margin for error by that much and expect not to pay a price for it.
The Mariners’ 3rd Major Issue: Injuries, obviously
What? You thought we were going to go through this whole exercise and not mention what the Injury Bug hath wrought on the Mariners?
No way, because it really is that bad. And even setting aside the injuries that have sapped depth from Seattle’s bullpen — Gregory Santos’ knee surgery especially stings, at least in the abstract — what will really break fans’ hearts is how many days the starters have lost to the IL compared to 2024:
- 2024: 89 days
- 2025: 80 days
Once again, we’re only a quarter of the way through the season. And yet, those two numbers (pulled from FanGraphs’ injury tracker, by the way) are nearly in line with each other already.
Most of the days missed for 2025 belong to George Kirby, who has been sidelined since spring training with shoulder inflammation. The others belong to Logan Gilbert and Bryce Miller, who are both out with arm issues.
The Mariners have, if anything, been lucky with Gilbert and Miller. Terms like “flexor strain” and “elbow inflammation” sound scary as all heck, but there’s a real chance of both being back before the end of the month. Kirby, meanwhile, has looked terrific during his rehab assignment and could return before the end of the club’s 10-game road trip.
Yet even if the M’s aren’t far from having a whole rotation again, the reality is that a lot of damage has been done already. And with the team clinging to a 0.5-game lead in the division, this damage may well be the difference between a return to the playoffs and another October on the couch.