As someone who strongly believes in the 80/20 rule and how it applies to successful NBA roster building, at first glance the NBA champion Spurs seem to be a bit of an exception. But, on closer examination, they really aren't.
Instead of having two or three great players to carry most of the load, the Spurs have four (Tim Duncan, Tony Parker, Kawhi Leonard and Manu Ginobili.) And because they have four great players, each one of them is not required to play as many minutes as "normal" star players, or do quite as much on the floor.
Since 2012 we have all been lauding San Antonio's balanced system - the fluidity of the offense, the still formidable defense, the minutes allotment, the perfect complementary bench pieces, the incredible coaching, etc. It's been a pleasure to behold. It's also very hard to pull off, especially in regards to chemistry. There is a reason no other organization has successfully replicated it.
I do not think San Antonio's feats are an exception to 80/20 rules as much as a perfectly balanced amalgam of them. Although this "current version" of the Spurs has won only one championship, they have been the best NBA team over the last three seasons. They have done it by still having great players, and simultaneously making subtle team management decisions better than everybody else. It is difficult not to be impressed, and even more difficult to imitate.