There are a multitude of reasons the San Antonio Spurs have won more games (.705 winning percentage) than any team in the NBA over the past seven seasons.
Tim Duncan is arguably the best player in the league every single year. Gregg Popovich has done a remarkable job perennially blending in new parts without having the team miss a beat. Manu Ginobili has taken his game from a sixth man extraordinaire to a "go-to" pressure performer in just three seasons and is now a bona fide star. Bruce Bowen is capable of locking up any wing player in the league and anchors the NBA's best defense. Tony Parker, although inconsistent, is still one of the top point guards in the league and can put relentless pressure on opposing defenses with his speed and ability to penetrate.
And so on. And so on.