Spurs were known for their tough and disciplined defense. But after Bowen retired, Big Shot Bod decided he had enough rings, and TD showing all the wear and tear on him over the years, Manu was a few steps slower than before. Spurs are no longer that top defensive team. They are still winning, but they use offense to offset the defense downgrade.
One more reason that Pop is a great coach - he plays to the strength of his players. It's been years, as evident as in all those playoff series, where Spurs and opposing teams exchanging points throughout whole series. The one against Mavs and OKC came to mind quickly.
So, last night's game wasn't just a fluke of Spurs, and quite normal for a Spurs team in transition.