A’s rookie starter shut down with mild UCL sprain

A’s rookie starter Mason Miller has been diagnosed with a mild sprain of the ulnar collateral ligament in his throwing elbow, the team informed reporters (including Martín Gallegos of MLB.com). He’ll be shut down from throwing for an indeterminate period of time until he’s no longer feeling discomfort.

Miller landed on the 15-day injured list with forearm tightness last week. It was almost immediately clear he’d be out for two weeks and the team announced yesterday that he was going for a second opinion. That raised some concerns about possible surgery. Miller will, fortunately, avoid going under the knife, though he seems likely to be out of action for an extended stretch. Gallegos notes the A’s are hopeful he’ll be able to pitch again at some point this season.

Injuries have unfortunately been a theme of Miller’s professional career. A third-round pick in 2021, the 6-foot-5 righty pitched only six rookie ball innings during his post-draft summer. He lost most of the 2022 campaign to a shoulder injury, tallying only 14 innings between three minor league levels. Miller returned to log 16 2/3 frames in the Arizona Fall League to close out the year.

After two minor league starts in 2023, the A’s called him to the big leagues for the first time. It was an aggressive promotion but the 24-year-old had shown well early on. He tallied 21 2/3 innings of 3.38 ERA ball over his first four starts, striking out more than a quarter of opposing hitters. Miller showed blistering velocity and looked to be the most intriguing starter in an A’s rotation that has been the league’s worst.

The organization will have to wait a while to get a longer look at the young hurler. Miller is clearly among the most talented pitchers in the system but he’s logged just 66 2/3 innings in two years as a professional. He’ll collect major league service and be paid at the MLB minimum rate while he rehabs. Miller won’t reach a full-service year in 2023 and is controllable through at least 2029.