Seattle Mariners Rotation Options If Bryce Miller Opens Season On IL

The Mariners have spent the last few years building a rotation that is supposed to be able to absorb something like this. Now they might actually have to lean on it. Bryce Miller’s oblique issue does not seem like a full-blown alarm bell just yet. The Mariners have not completely shut him down, and right now it feels more like they are waiting for the soreness to ease before getting him back into throwing progression.

But with Opening Day creeping closer, this is starting to feel a lot less theoretical. What looked like a minor spring inconvenience is beginning to look more like a real roster decision. Ryan Divish of The Seattle Times, pointed to the two most likely fill-in options if Miller misses the start of the season. But it’s a little more interesting than that. Let’s take a look at Seattle’s options.

Who Could Replace Bryce Miller In The Mariners Rotation?

Emerson Hancock

If Seattle wants the most straightforward and obvious answer, it’s definitely Hancock.

He is the familiar option. He has already been asked to step in when the rotation got thin over the last two seasons, and there is at least some internal comfort in knowing what that looks like. That does not mean it has always looked great. The Detroit Tigers made sure of that early last season. But it does mean the Mariners have already crossed this bridge with him before. Over the past three years in the majors, Hancock has logged 162 2/3 innings with a 4.81 ERA, a 15.6 percent strikeout rate, a 7.6 percent walk rate, and a 40.1 percent ground-ball rate.

Facing Nico Hoerner, who doesn't strike out often, Emerson Hancock go him with a sweeper. pic.twitter.com/LEYMDwKtR0
— Ryan Divish (@RyanDivish) March 12, 2026

The pedigree still carries some weight because former top-six picks do not just stop being interesting. But at some point, the draft status becomes background noise and the actual big-league performance becomes the louder truth. And so far, Hancock has looked more like useful depth than some obvious breakout answer.

Still, there is a reason he remains firmly in this conversation. He is stretched out, he has starter experience, and his spring line has at least given the Mariners something to work with. Hancock has posted a 4.76 ERA in 11.1 spring innings with 17 strikeouts and a 0.79 WHIP, which is the kind of stat line that at least keeps the door open for a short-term fill-in role.

If the Mariners want the cleanest, least dramatic solution, Hancock is probably it. Whether he is the best solution is where the debate starts.

Cooper Criswell

Criswell is the more interesting case because he fits as a roster answer. He’s out of minor league options, which means Seattle cannot casually shuttle him around while trying to preserve depth somewhere else. If he is staying, he probably needs to have an actual job. That reality alone gives him a real shot here, especially since his spring has been strong enough to justify the conversation. He has a 1.74 ERA in 10.1 spring innings with 10 strikeouts and a 0.87 WHIP.

There is a pretty obvious reason Criswell keeps showing up in this conversation. He handled 99 1/3 innings for Boston in 2024 with a 4.08 ERA, did a decent job limiting damage, and kept the ball on the ground. Then in Triple-A in 2025, the strikeout numbers jumped even if the command got a little shakier. Seattle did not just stumble into him either. He is the kind of arm teams keep trying to hang onto, which is how he ended up bouncing through Boston and New York before landing with the Mariners.

The part that makes Criswell feel a little dangerous is also the part that makes him hard to fully trust. He’s not going to overpower you with his stuff. His fastball rarely sniffs 90 regularly, which means the margin for error is tiny.

Still, if the Mariners are trying to solve two problems at once — cover Miller’s innings and avoid losing a useful arm for nothing — Criswell starts making a lot of sense. He may not be the flashiest answer, but he might be the most practical one.

Jhonathan Díaz

This name probably should not be dismissed as quickly as people might want to. No, he is not the favorite. No, Divish nor anyone else for that matter have identified him as one of the most likely options. But if you are looking for a classic Mariners depth move that sneaks into relevance when things get weird, this is exactly the kind of profile that fits.

Díaz feels like the sneaky name here. He has already done the spot-start, hold-things-together job before, so this would not exactly be new territory for him. In 17 big-league appearances from 2021 through 2025, including seven starts, he has a 4.66 ERA over 46.1 innings with 33 strikeouts.

And while none of that screams future ace, that is not really the point. The point is that he has shown he can give an organization real coverage when needed. He also put up a 2.98 ERA in 11 Triple-A starts in 2024 and has opened this spring with 3.0 scoreless innings, no hits, no walks, and two strikeouts.

That is why Díaz works as the dark horse here. He’s a lefty who’s been in this kind of role before, and Seattle clearly thought enough of the profile to bring him back into the mix.

Would the Mariners really choose him over Hancock or Criswell for the first opening? Probably not. But if they want a less conventional answer, or if this turns into more of a short-term patch than a true rotation replacement, Díaz is at least the kind of sleeper name worth keeping in the back pocket.

Bryce Miller’s Replacement Is Probably Coming Down To Two Names

At the end of the day, this still feels like Hancock versus Criswell, with Díaz hanging around as the deeper-cut contingency plan.

If the Mariners want the safest organizational answer, it is Hancock. If they want to solve the roster puzzle while rewarding the better spring, it is Criswell. If they want to get weird for a minute, Díaz is the dark horse lurking in the background.

The bigger point, though, is that none of these names are Bryce Miller.