At this point, one might assume Gilliam will trade in his Seahawk helmet for a 49er helmet. The 49er contract guarantee and amount makes sense given the differences in cap room, anticipated 49er blocking scheme changes after coming off a poorer year, and bet on Gilliam as an emerging linemen who has yet to peak.
Gilliam takes with him 3 years of accumulated development and the balance of all snap experience at right tackle.
The Seahawks return, very nearly, back to square one to create competition at right tackle.