The Seahawks are a talented bunch. Some of the areas of the team, though, are much more experienced than others. Take the receivers for instance. A room of newborn babies has nearly as much NFL experience as does the Seattle receiving group. And the secondary is only slightly more veteran.
Injuries are going to take some kind of toll on every professional football team. Attrition happens. Teams can sign players off the street to replace those who have fallen on the field of play. Or they can look towards their practice squad for help. Though Seattle has set their active roster, there are several players they signed to their practice team that could easily help this season.