10:10 pm: Dunn doesn’t sound overly concerned about the injury, telling the Mariners television crew his shoulder “just didn’t bounce back” the way he’d expected after his start on May 29 (h/t to Ryan Divish of the Seattle Times). Dunn believes he’ll only need a few days of rest before he can ramp activities back up.
8:45 pm: The Mariners announced they’re placing right-hander Justin Dunn on the injured list, retroactive to June 1, with inflammation in his throwing shoulder. Fellow righty Robert Dugger has been recalled to take his active roster spot. The team did not provide a timetable for Dunn’s potential return.
Dunn has made nine starts for Seattle this year, tossing 45 1/3 innings of 3.18 ERA ball. That’s high-end bottom line production, although his underlying metrics indicate he’s been rather fortunate to keep runs off the board at that level. Dunn’s striking out batters at an average 23.4% clip, but he’s issuing walks at a very high 14.1% rate. Opposing hitters have only managed a .196 batting average on balls in play against Dunn, who has stranded an unsustainably high 82% of baserunners to this point.
To his credit, Dunn has missed a few more bats than ever this season. The aforementioned strikeout rate is his career-best mark, as is his 9.9% swinging strike rate. He’s also working with career-high velocity. Dunn’s average four-seam fastball speed sits at 93.7 MPH, up more than two ticks relative to last year’s mark. His development is welcome news for a Mariners club counting on the former Mets first-rounder to cement himself as a long-term rotation option.
Seattle has rolled with a six-man rotation throughout the season. Dugger, who has started a pair of his eight MLB appearances, seems likely to step into that mix. Alternatively, the M’s could allow each of Yusei Kikuchi, Chris Flexen, Logan Gilbert, Justus Sheffield and Marco Gonzales to take the ball every fifth day. The Mariners have remained committed to the six-man starting staff all year, but depth starters Nick Margevicius, Ljay Newsome and Erik Swanson are all now on the injured list.
Seattle also announced they’ve outrighted corner infielder Eric Campbell to Triple-A Tacoma. Campbell, who has already cleared waivers, has the right to reject the assignment in favor of free agency, having previously been outrighted in his career. He played in four games for Seattle this year, his first big league action since 2016. The Mariners now have two vacancies on their 40-man roster.