George Kirby to start season on IL with shoulder inflammation

Seattle’s rotation will start the season short an ace.

Seattle Mariners general manager Justin Hollander announced to media today that RHP George Kirby has been shut down from throwing due to inflammation in his shoulder, that will have him starting the season on the injured list. Hollander explained that there was no structural damage shown on the MRI Kirby underwent, nor did they have larger concerns about Kirby’s health. His velocity and effectiveness during his outings was as expected, however Kirby felt the pain and discomfort between outings at an elevated level beyond normal recovery thresholds. Overruling Kirby’s desire to continue pitching, the club is pausing his throwing until the inflammation subsides.

Though that pause could be as minimal as a week, the timing of the delay is such that Kirby will not be quite ready for the start of the 2025 season at full build up. With that in mind, Hollander expects Kirby to start the season on the 15-day IL for pitchers, rejoining Seattle hopefully after missing just the minimum time. If, as is hoped, Kirby merely misses the minimum time and sees the inflammation recede swiftly, he could end up missing just two turns through the rotation. Seattle’s season opens with seven straight tilts, but features off-days on the first two Thursdays of April, the latter of which would be the 15th day of the season. Should Seattle wish to, they could put Kirby’s replacement in the 5th slot of the rotation, allowing them to align against the Tigers on Monday, March 31st, and then at the Giants on Sunday the 6th of April, which with the off day could line up Kirby for an extra day of recuperation and a return on the 12th of April at home against the Rangers.

That’s the best case, of course, as Kirby’s malady is one that has presaged more lengthy issues for many hurlers. The lack of structural issues is a good one, however, and while there are plenty of examples of pitchers whose shoulder inflammation led to something far worse, it can just as easily be merely what it’s advertised. For a recent Mariners example, 2022 reliever Diego Castillo hit the 15-day IL midseason with shoulder inflammation in late July, missing the allotted time before returning to post strong numbers for the final two months of the season without incident.

Losing Kirby for any amount of time is a sizable step down, however, as Seattle’s rotation depth is passable but without a track record of success. First up will likely be RHP Emerson Hancock, whose new pitch mix entered the petri dish beneath Jake Mailhot’s microscope recently. Beyond Hancock, Seattle has several starting pitchers in camp, including NRI veterans LHP Jhonathan Díaz and RHP Casey Lawrence, alongside swingman RHP Blas Castano on the 40-man roster.