I'm sure someone else already said this, but it's a win-win for the Sox and Sale. Sale guarantees himself a payday and at worst he will be underpaid for a few seasons, no big deal.
As far as the Sox are concerned, best case they lock up a premier starter for cheap. Worst case they aren't on the tab for too much per year if Sale's health goes south.
Proudly eating crow on Robin (for now at least)