The Seahawks will get back two starters after their week seven bye. Linebacker K.J. Wright and tight end Ed Dickson will return. Running back J.D. McKissic might not be ready week eight (or he could be), but he will definitely return from IR soon. And he needs to replace C.J. Prosise on the roster.
I know it sounds a bit odd to prefer McKissic over Prosise based on the assumption that McKissic will stay healthier than Prosise. McKissic has missed all of 2018 with an injury. But Prosise has never stayed consistently healthy over his three year career.