We haven’t seen baseball this bad in Seattle in 50 years.
The Mariners were outscored 169 to 95 in August on their way to an 11-16 record. That’s a run differential of -74. That’s bad. That’s historic. That’s the second worst run differential in a calendar month in team history. The only month worse? August of 1977, the team’s inaugural season — you know, the one they “celebrated” earlier this month.
There’s obviously two components to run differential: the run scoring, and the run allowing. The Mariners
run scoring in August wasn’t good. They scored 95 runs, which was the fewest in the majors. Their 94 wRC+ (18th) looks a bit friendlier, but there’s no way to spin it as anything other than a bad month for the lineup. That’s not uncommon in Seattle. It wasn’t even their worst month this season.
The novelty of August 2026 instead comes from a total implosion by the Mariners pitching staff. They gave up 169 runs, or an ERA of 5.97. Only the A’s gave up more runs (174). We can see how quickly the Mariners sunk from mediocre to awful.
What’s unique about the Mariners is they did this while playing half their games at T-Mobile Park, the most suppressive stadium in the majors. That’s what ERA- is for. It adjusts for both the stadium and the league’s run scoring environment. The Mariners posted a 154 ERA- in August, meaning they gave up 54% more runs than average. Nobody else really came close to that level of futility. In fact, August 2026 was the Mariners all-time worst pitching month by ERA-, with data going back to 2002.
In general, I don’t really like ERA to evaluate pitchers, because it holds the basic assumption that Bobby Witt Jr.’s defense has the same impact on the box score as J.P. Crawford’s. That is, of course, ridiculous, and also directly relevant here. The Mariners defense in August posted -16 OAA — yes, that’s correct, -16 OAA — which was the worst in the majors by a lot and a number so tremendously bad I went looking for whether that was some sort record, before quickly finding the Mariners posted -18 OAA in April. We knew the defense was going to be bad heading into the season, and it’s indeed been the worst in the majors. This is one thing to keep in mind when thinking about the performance on the mound.
Anyways, that’s why I prefer FIP when evaluating pitchers. It helps isolate the things a pitcher has direct control over: strikeouts, walks, and home runs allowed. The Mariners FIP- in August wasn’t quite as bad as their ERA-, but it was still a league worst 131.
Now, FIP and FIP- are great, but with just a few more adjustments (that are too technical to explain — I.e., I don’t understand them), we get pitcher fWAR. To me, this is the most complete pitching stat there is, and it’s become my daily driver. The Mariners in August posted -0.7 WAR, confirming them as far and away the worst pitching staff in the majors. In fact, the Mariners -0.6 WAR since the All-Star break is about 1.8 WAR behind the A’s in 29th. This has been the worst pitching staff in the majors for nearly two months.
What’s interesting is the Mariners actually reached the All-Star break as the very best team in the majors by WAR. We’d never seen them pitch so well and so consistently in an era largely defined by quality pitching (even if that quality has always been a bit exaggerated). At one point, they had so many good pitchers in it wasn’t clear how they could use them all. That feels like a distant memory now.
I don’t know what spurred the sudden collapse, but I have some theories. I think the six-man rotation is at the center of all of this, and my skepticism hasn’t changed since they adopted it back in June. I think the structure took an arm away from an already shallow bullpen, and I think the rotation was asked to cover far too many high-stress innings as a result. I think the arrangement collectively wore them down over time, and I think everyone is now just kind of gassed. I think the decision to call up Kade Anderson, who’d never thrown more than 80 pitches in a game as a professional, was desperate and shortsighted, and I think it only added to the strain of their death throes. I think it was a collective effort that snowballed into some of the worst pitching we’ve ever seen in Seattle.
We saw this play out a few weeks ago when they suffered dual slaughterings of 22-0 to the Brewers and 19-2 to the Cubs. Miller was clearly struggling, again, to get through even four innings. After multiple short outings in the days leading up, Dan Wilson’s bullpen had limited availably. That meant he was forced to stick with Miller, who folded anyways. They eventually just ran out of relievers while trying to cover five-plus innings for the umpteenth time, and that turned the game over to the position players, who turned a couple bad losses into spectacles worthy of national headlines.
The week reinvigorated scrutiny of Wilson’s in-game management, but that doesn’t seem quite fair, given how bad and shallow his pitching staff has been. There are, somewhat literally, no good options for him in either the rotation or the bullpen. I’m more likely to point the finger at the arrangement he was saddled with, largely because general manager Justin Hollander was aware of the pitfalls just last year:
“The unfortunate thing about the roster rules is you only get 26 spots, and you only get 13 pitchers. And when you add a sixth starter, you take away a reliever. When you add a sixth starter, sometimes your starters pitch every six days, sometimes they pitch every eight or nine days. Starting pitchers are fussy. They don’t like that. They like to stay on a regular schedule. They like to know when they’re pitching.”
Back to my thoughts: I think the six-man structure was justified for a few turns, when Miller initially appeared to have outgrown his training wheels. But I think the front office should have been quicker to acknowledge the collective strain. I think they dawdled far too long on the question of Bryce Miller, when it was clear he couldn’t cut it as a starter after just a few outings. I think, frankly, they wanted to keep the “starter” label for certain pitchers with an eye toward the offseason, operating with the assumption the division would ultimately be handed to them. Most of all, I think all of this could have been avoided had they simply come into the season with a better and deeper bullpen, something that was easily identified in the preseason (and last year’s postseason). I think the situation was a series of administrative errors by a front office that found itself with too much of a good thing.
Regardless, the Mariners right now are among the worst teams in the majors at hitting and base running, and they are definitively the worst team at pitching and fielding. They don’t do anything well. They don’t do anything even close to average. If you want to call them the worst team in the majors full stop, I wouldn’t argue otherwise. We haven’t seen a performance like this in 50 years. There’s still a month left to play.
