How in the Heck Is a Rotation This Good Going To Miss the Postseason?

About two weeks ago, Kyle Kishimoto wrote about a shift in the AL West race as the Astros, who had been trailing the Mariners all year, pulled level in the division. Ordinarily, I wouldn’t revisit a topic so soon, especially because Kyle was himself issuing an update to his own previous appraisal of Seattle’s success. But between Kyle’s two posts, the Mariners blew a 10-game division lead to Houston. And in the two weeks since then, well at the risk of steering directly into stereotype, let’s take a look at a graph.

On the morning of August 5, when Kyle’s second piece ran, the Mariners were still actually slight favorites to win the AL West. In the ensuing 15 days, their division title odds dropped by 43.4 percentage points, to just 10.8%. Seattle’s odds of making the playoffs in any fashion are now just 16.4%, which is down 41.6 points. Only three other teams have seen their playoff odds move even 20 points in either direction in that time. One is the Padres. The other two are the Astros and Royals, two of the major beneficiaries of the Mariners’ ongoing slide.

The Mariners are behaving in such a manner that I am going to have a stroke restraining myself from peppering this entire post with nautical idioms. The voices in my head are telling me that it wouldn’t be hackneyed to say the Mariners are “taking on water” or “lost at sea” or “adrift and rudderless.” Those voices are wrong, but they are loud.

Every other team in the AL playoff bracket had better hope the Mariners sink. (Sorry, I can’t help myself.) Because if they do manage to limp into the postseason, they have one unit that will make them inherently dangerous: Their rotation.

After all this consternation, the Mariners are still (if only barely) leading the majors in starting pitcher WAR. They also lead all 30 teams in innings pitched by starters, and are second in K-BB% and third in ERA-. If you want to pin this losing streak on anyone, you can’t blame Seattle’s starters.

The high-water mark of the Mariners’ season was June 18, when they were 13 games over .500 and 10 games up on both Houston and Texas, who were tied for second in the division. Since then, Seattle is 20-31, which is the second-worst record in baseball, ahead of only the Chicago White Sox. (The White Sox, God save them, have somehow won only 10 of their past 52 games.)

During that 20-31 run, Seattle’s starting pitchers have the third-best ERA- in baseball, the third-best K-BB%, and the best walk rate by an enormous margin. Outside of Andrés Muñoz, Mariners relievers have been pretty bad on aggregate; non-Muñoz relief arms have one save and six blown saves in their past 51 games, and an ERA of 4.59.

Now, six blown saves (nine including Muñoz’s efforts) in two months doesn’t explain everything that’s gone wrong in Seattle. For that, you have to turn your attention to the offense: .206/.299/.355 since June 19. That’s a WRC+ of 93, which is somehow still 20 points better than Chicago’s but — more relevant to this issue — 20 points worse than Houston’s.

Worse than that, Seattle’s offense has been streaky and bad in big moments. Mariners hitters have the second-lowest WPA since June 19, more than a run worse than anyone other than the White Sox. Over their past 51 games, the Mariners have scored two or fewer runs 23 times, which is tied for second most in the league. They’ve been held to one run or less 13 times, which is more than the Royals and Astros put together, and Seattle is — as you might imagine — 0-13 in those contests. The Mariners have been goose-egged as many times in the past two months as the Phillies have in the past 12.

I didn’t mean to spend this much space ragging on the Mariners’ offense — or to be more accurate, their paucity thereof. But it is important to underscore that in an age where bullpen games are incredibly common in the playoffs, a team with five very good starting pitchers is trending toward being left out of the postseason altogether.

Consider the following population of players: Pitchers who have thrown 50 or more innings as starters this season and are currently (i.e. per RosterResource) in the starting rotation of an American League team with at least a 10% chance of making the playoffs, according to our playoff odds. This is not the full list of potential playoff starters; the Guardians, for instance, have only two players on this list and are absolutely going to the postseason. Gavin Williams fell just outside the innings cutoff, but you’d better believe that he’ll make a playoff start for Cleveland if he’s healthy. The arbitrary endpoints have to end up somewhere.

But the 36 (it was 37, but Zach Eflin went on the IL while I was writing) who fit those criteria are representative of the pitchers who would make the starts in the AL postseason bracket this coming October. You can come up with your own list of where each of the Mariners’ five starting pitchers would end up in a fantasy draft of available rotation options for the AL playoffs, but here’s where they rank among those 36 starters.

One thing that’s become a real drag about working in baseball over the past few years is how quickly the role of the starting pitcher has changed, especially in the context of the playoffs. So much has changed so quickly that most fans, and even most generalist sportswriters, don’t appreciate how rare it is for a team to put together an entire five-man rotation of starting pitchers who can turn over a lineup more than twice in a playoff game. And then to keep such a rotation healthy over the course of the season.

Last season, all four teams who played a best-of-seven series had at least one bullpen game in the postseason. (I guess we can argue about the Astros in Game 4 of the ALCS, where José Urquidy was pulled in the third after allowing three straight baserunners, and Hunter Brown threw three scoreless innings in relief. Does that count as a bullpen game or did Urquidy just get knocked out early?) Three of those teams — the Astros, Phillies, and Rangers — spent more on their top three starters than the A’s spent on their entire 26-man roster. And they still found themselves short of trustworthy starting pitchers.

Building a rotation like the one the Mariners have is arguably harder than making the playoffs. Surely fewer teams will accomplish the former feat than the latter this season. So if they do end up missing the postseason after building the most difficult part of a postseason-worthy roster, that’d be astonishing. A team with a rotation this good ought to be (winces) unsinkable.