The only way I can wrap my head around this is three things are true:
1) Sitton's back is worse than previously thought. We know it affected him on the field last year and that it dictated his offseason.
2) 6.85M is about fair market value for a solid starter, and cheap for a resume like Sitton's. This move must really help the beancounting of next years free agent exodus. If cap space alone were the reason, they would have cut him months ago.
3) When Ted said "best for the team and growth of the offensive line" he wasn't talking about youth for the sake of youth with turds like Lane Taylor or Barclay. For the team to grow in any meaningful sense this gets a guy with serious potential on the field. Put me in the Bak, Spriggs doubleswitch camp.