A lot of that has to do with how the Spurs play.
They just play such a high variance brand of ball with all the 3s they take and the constant lineup shuffling. It is the right way to play for a team that doesn't necessarily have a signature go to guy but it lends itself to some lopsided scores both ways. They tend to rely on roleplayers more than your avg elite NBA team and as we know these guys can be pretty streaky
Last year in the finals only had 3 out of 7 competitive games as well.