For me, the problem is not with Durant, it is with the team they have built around him. They really have done a terrible job of putting players that compliment Durant together.
Their best players other than Durant are a very solid all around player in Green...who happens to be a prototypical SF, which is the same position Durant needs to be playing...and Westbrook, who is a shoot first PG who needs the ball in his hands to be successful.
They also have no real shot blockers, and really no real starting quality PF's.
Yes, Durant needs to improve defensively, but he is never going to be on a winning team, until he is matched up with some defensive big men (Chandler would be perfect), and a pass first PG.
Ideally, he would also be in an uptempo system.
I think having a heady SG like Harden was a great move.
What they ought to do is feel out Portland to see if Portland would be willing to work out a Jeff Green+Krstic/Mullens for Outlaw/Przbilla
A starting 5 of Westbrook/Sefelphsa+Harden/Durant/Collison/Pryzbilla could be a decent team. Fringe playoffs maybe.
Then, they'd still have a bench of Outlaw at the 3/4, Etan Thomas and Krstic or Mullens, and Kevin Ollie
Its not a ring team but it's solid.
I think Green is a lot to give up for Pryzbilla (even if Outlaw is coming too), but I like the thought.
Ultimately, I think they have done a nice job of collecting assets, because even though they don't fit together, they have picked guys whose value has grown since being drafted IMO. But to take the next step, they need to now start considering turning those assets into the right pieces to put around Durant.
The real tough one for me I think is going to be Westbrook. I really can't envision him being a good fit with Durant. Its one thing if you have a shoot first PG, but Westbrook isn't even a good shooter. Basically, he reminds me of a Dwayne Wade type. And I just don't think you have have that along with Durant. But will they be able to get good value for him?
Personally, I think they should be talking with Memphis about Mayo. I think Mayo would be the perfect running-mate with Durant. He can handle the ball, distribute it, as well as play off of it, and knock down the outside shot. If they could build a young perimeter core around Mayo, Harden (who I love), and Durant, I think they would be on the right track. Then they could try to turn Green (or their cap space) into a big man, and they would be on their way.