I think people have (sort of) posted this and understand this, but just to reiterate, OKC just signed Perk to the exact same deal that the Cs could have offered him.
My understanding is that it wasn't an issue of the Cs having the capability of offering the years and dollar amount, but rather DA didn't WANT to offer this extension.
Now if Perk had hit the open market and gotten a huge offer from a team under the cap then that is another story, but the Cs could have offered Perk four years and $35 mil. They decided not to.