Seahawks head coach Pete Carroll said Monday that Johnson (ankle) suffered a serious injury and is going to miss some time, Liz Mathews of USA Today reports.
Carroll noted that he doesn't know the specifics of Johnson's injury, but the head coach added, "I do think it's a stress fracture kind of thing that he is dealing with. That's somewhat of a significant injury." The linebacker was claimed off waivers by Seattle when Shelby Harris was sidelined with a lower-body injury and garnered a solid depth role, but it appears like he'll be sidelined for a few weeks and may even end up on IR.