The 49ers offensive line hasn’t been the same since their loss in the NFC title game against Seattle back in January 2014.
From that starting group, only two starters remain: Joe Staley and Alex Boone.
Jonathan Goodwin left as a free agent following the loss and both Mike Iupati and Anthony Davis left this offseason, one going to Arizona as a free agent (Iupati), and one taking a break from football to recover (Davis).
All along, the 49ers knew that there was a very real possibility that Iupati would eventually leave, simple economics- they didn’t have the money to keep him around.