Ever since the Sonics transformed into the Thunder and relocated from Seattle to Oklahoma City, the identity of the franchise has been youthful talent and substantial roster flexibility. 

Sam Presti collected assets and preserved cap space while allowing his core to mature, improve and naturally reveal where they needed to be adjusted.

Jeff Green very evidently became the dispensable player since he doesn't have the high-end game of Kevin Durant and Russell Westbrook, and his value to the Thunder as a jack of all trades was dubious relative to his minutes and his likely financial value on the open market.

The Thunder converted Green, along with Nenad Krstic and a first round pick from the Clippers into Kendrick Perkins, one of the best interior defenders in the NBA. They cemented Perkins into their team long-term a few days later by agreeing to a $34.8 million extension over four seasons. 

Westbrook, who has the same representation as Perkins, will sign a max/near-max extension this summer when he becomes eligible.

While Oklahoma City still has a large collection of tradable assets and they still need to figure out how James Harden fits, but the vastness of that flexibility is now gone.

In terms of the absolutely essential members of their core, the Thunder are locked into Durant, Westbrook, Perkins and Serge Ibaka.

For the time being at least, Oklahoma City's supporting rotation players are Thabo Sefolosha, Harden, Cole Aldrich, Eric Maynor and Daequan Cook, which gives them one of the deepest teams in the NBA.

Love it or like it, this is essentially what the Thunder will look like for the next five seasons.

The Thunder will certainly add and subtract a few players here and there, but their ability to do something of great magnitude is now limited. A major recalibration of Oklahoma City would mean doing something with Ibaka or Westbrook, and I can't see that happening in the same way San Antonio trading Tony Parker or Manu Ginobili wouldn't happen.

When someone does a substantial remodeling of their house, there is sometimes a sentiment that they don't want it to be over because it means they will need to live in it and they're struck with the choices they made. 

I'm not sure if Presti experienced that feeling, but he has unquestionably passed through the heavy-lifting phase of his job with this version of the Thunder and the onus is on Durant and Westbrook to be as great as they are capable of being. Unlike superstars like LeBron James when he was with Cleveland, Chris Paul and Dwight Howard, Oklahoma City's best players have far superior supporting casts that are capable of greatly enhancing their title chances instead of merely being dead weight to carry. If Durant and Westbrook are incapable of winning a title over the next five seasons, it will be due to the fact that they weren't good enough individually. 

While that is a pressure situation to be in for any player, it is how we define greatness and both Durant and Westbrook should be grateful to be put into that type of opportunity.

As for the extension itself on financial terms, it all comes down to the health of Kendrick Perkins. If Perkins is on the floor, he is worth far more than $8 million annually and is therefore a price that should be considered fair from their perspective.

Since Presti already sent back Tyson Chandler in a trade because of discouraging medical evidence, we have to assume Perkins' knee checked out long-term.

Perkins' value is in defending the game's best interior scorers without the need for a double-team, which has an obvious carryover effect to the ability to prevent scoring from opponents' other options.

On the offensive end, Perkins doesn't bring nearly as much as other big men, but the Thunder already possess enough high quality scorers. He sets a monster screen, though he unfortunately needs to roll to the bucket to be a scoring threat and doesn't have a reliable jumper to be called upon for a pick and pop. Ibaka's jumper is still inconsistent, but I believe in his ability to hit looks around the elbow on a consistent basis in time.

With Perkins and Ibaka as Oklahoma City's starting frontcourt, there is even a greater imperative for Durant to improve his post scoring because they aren't getting it from those two. This is the greatest weakness of the Thunder moving forward.

Grade for Thunder: A

Perkins' best friend on the Celtics was Rajon Rondo, and like him, he took considerably less than what he would have received on the open market. Rondo would have received the max last summer and Perkins would have seen something closer to $10 million per year, so he''s not leaving nearly as much on the table. But for Perkins, that is the price for pre-CBA stability and also for being a clear injury risk.

The Celtics offered $22 million a few weeks ago, so this deal represents a considerably more aggressive offer. I'm sure Perkins envisioned himself remaining with Boston and he has now committed his future to a team he has never stepped onto the floor with, but it isn't any different than signing a free agent deal in that regard. Perkins would choose $35 million with the worst team in the NBA over $22 million, so the fact that he gets such a competitive financial deal from a team with the stability to compete and complete front office competence is a positive ancillary benefit.

Grade for Perkins: B+