Being old, I would suggest reviewing Red Auerbach's approach for two reasons, the second, perhaps being most important. (I would like to address the "different era" objections here. Yes a different era, but, good Lord, not THAT different. Look at the man's draft record/team building record.)
1. Red used the draft to acquire the pieces to beat other GM's.
2. Ainge is Auerbach's protege. Unquestionably, Ainge has and will follow Auerbach's lead because it worked the other 17 times.
Yes, like Belichick, any winning program has been lucky. You must however, MAKE that luck by planning, studying, fighting and doing these things consistently for an adequate length of time. All is not won in a season or two.
The Thunder sure have a good ball club, but they are flawed enough to expose Presti's building principles and affirm Auerbach's.
Red got his centers. They had to have offensive ability, but, they had to fight to the very end on defense. HAD TO. Russell, Cowens, Parish all had solid offensive games along with the commitment to defense. Sam Presti skipped this step while assembling a highlight reel generating offensive team. San Antonio, obviously got it right with Tim.
Ainge, hired by Auerbach, gets Garnett. Auerbach was whispering in his ear from Heaven..."This Garnett fights to the end, put him underneath. He's the defender you build around..."
Auerbach always had a "defensive leader" on the court. Every town needs a sheriff and it helps if this sheriff is bigger than everyone else.