The headline tells you what has transpired. Charlie Furbush has been activated from his rehab assignment and re-promoted back to the Mariners. Shawn Kelley has been sent back to Tacoma.
The why, I don't know. I would have thought that Carter Capps is surely the most expendable person in the bullpen at the moment as he's a bit redundant with Stephen Pryor in terms of stuff and role and he also has some obvious command issues to hone. Shawn Kelley has been as good as you'd conceivably want. I feel like I'm missing something here.