Orioles ace prospect Colin Selby’s season ends after right shoulder surgery, while Ryan Mountcastle’s oblique strain lingers

The Orioles will be without right-hander Colin Selby for the rest of the 2026 season after he underwent season-ending surgery, according to comments from Mike Elias, the team’s president of baseball operations. Elias told reporters, including Roch Kubatko of, that Selby had surgery on his right labrum and rotator cuff earlier this week. The recovery plan is expected to keep Selby on the injured list into the 2027 season.

Selby’s timeline is a significant development for Baltimore’s pitching depth, particularly because it removes an available option not just for the closing weeks of 2026 but also at the start of the next campaign. The injury nature, involving both the labrum and the rotator cuff, suggests a longer rehabilitation window than the typical short-term shoulder ailment, and Elias’ remarks frame it as a rehabilitation process that extends beyond the current year.

At the same time, Baltimore’s lineup picture has another wrinkle with first baseman Ryan Mountcastle. Elias described Mountcastle’s issue as a “pretty significant oblique strain,” and the update indicates that the injury has extended beyond an initial recovery window, pushing the first baseman’s absence further than expected. Mountcastle’s oblique problem now threatens to disrupt not only late-season workload planning but also spring-to-spring continuity for Baltimore’s everyday middle-of-the-order roles.

For a club that often manages player availability with an eye toward both immediate performance and postseason durability, two simultaneous injury storylines can compress roster flexibility. Selby’s shoulder surgery removes a pitching piece that the Orioles would normally be evaluating in-game and workload terms, while Mountcastle’s ongoing oblique recovery complicates the team’s ability to settle into a steady batting order and positional rhythm.

The Orioles’ next steps likely hinge on medical reassessment and on-field replacements rather than speculation. With Elias placing Selby’s recovery into 2027, Baltimore will need to redistribute innings and bullpen usage during the remainder of this season and carry that planning into the offseason. Meanwhile, Mountcastle’s oblique strain raises the question of when he can return to full swing mechanics and base-running intensity without risking setbacks.

What to watch next is how Baltimore structures its approach to July-to-September roster roles for both positions. Selby’s absence into 2027 makes the pitching depth question longer-term, while Mountcastle’s extended ailment makes the lineup question immediate. For fans tracking the Orioles’ internal pipeline, this is also a reminder that midseason injuries can reshape evaluation priorities, forcing the organization to lean on other arms and hitters to cover for gaps while players rehabbing progress through their timelines.