What to watch for as Miller returns from IL for '26 debut

4:40 PM UTC

HOUSTON -- is ready to roll.

The Mariners activated the right-hander from the 15-day injured list on Wednesday, when he’ll make his much-anticipated 2026 debut against the Astros at Daikin Park. Lefty José Suarez was designated for assignment to clear a roster spot.

Here are three things to watch, for this outing and long term:

The stuff
This is what everyone in the organization has been so bullish on -- after his epic October, his early flashes in Spring Training before the oblique issue and throughout his four-outing Minor League rehab assignment.

Pitch-tracking data isn’t publicly available for the two starts he made at High-A Everett, but at least for the two starts at Triple-A Tacoma, Miller averaged 96.7 mph on his four-seam fastball while topping out at 98.8 mph.

“I don't think I've had a fastball -- a single fastball -- lower than last year's average,” Miller said. “So, we'll see how long we can keep that up. But yeah, come out firing and have some fun.”

Remarkably, a quick fact-check almost verifies that assertion. Miller’s heater in 2025 -- when he was laboring through bone spurs in his pitching elbow -- averaged 94.8 mph. He threw only one lower than that at Tacoma.

OK, velocity is great, but what about the rest of his arsenal?

Miller is still throwing each of the seven pitches he did last season, per Statcast -- the four- and two-seamers, splitter, sinker, knuckle curve, slider, sweeper and cutter, the last of which might be one worth watching more intently.

“Just another fastball option, and it's been locating it well every time I've thrown it for the most part,” Miller said. “The shape has been real consistent. It moves quite a bit.”

Miller installed at the outset of 2025 but used it just 1.1% of the time.

“When I threw it, it was always like, kind of just hoping it would cut,” Miller said. “This year, every time I've thrown it, it's been super consistent, late. Kind of playing the back of the righty-lefty game -- fastball/sinker and fastball/cutter.”

The mound presence
Miller anticipates natural jitters, even if it’s so out of character.

Beyond the debut, this is a venue that he grew up attending regularly and against a team he cheered for that’s now a division rival. Miller is a native of New Braunfels, 175 miles west of Daikin Park, and will have a large contingent of family and friends here.

That said, expect his trademark, even-keel persona to prevail.

Because he is, objectively, Seattle’s most grounded starter. And that was an attribute that really shined last October, when he put the Mariners in position to win in each of his three starts -- including a gritty effort in Game 1 of the American League Championship Series in Toronto.

That all came after two IL stints related to the bone spurs, and overall, a soul-searching regular season, when he had a career-worst 5.68 ERA (67 ERA+, where league average is 100).

“Last year obviously didn't go as I had planned or envisioned the season,” Miller said. “But yeah, I finished strong. Postseason, I felt great. And yeah, I'll just carry that momentum. The original plan was to carry it to Spring Training. But now, now we're here, and now it's time to pick up where we left off.”

The 6-man rotation
Miller’s return adds complexity to the rest of the starting staff, since the club will not subtract any of its other five starters -- at least this time through. They are in the midst of 13 games in 13 days but are off again next Thursday, May 21, after which they’ll reassess.

It’s possible that they piggyback Miller with Luis Castillo at some point, but those plans are far from solidified and could easily change based on individual performances, health and more. Miller has been on a six-day routine since beginning the rehab assignment on May 18 and will be on a seven-day for Wednesday’s start.

After all, Miller was arguably the starter that the front office was most eager about entering 2026, based on how strong he finished 2025. If he’s good to go, logic would suggest they’ll want to maximize his exposure.