You seem to be forgetting that in order for the Spurs to make the finals last season, OKC, Lakers, all had tremendous injuries in the playoffs. I'm guessing the injuries the Spurs are suffering now is karma for that.
Also, keep in mind other teams have gotten better. Portland, who was a no factor last season, has now emerged as a true Achilles heal of the Spurs. OKC is having a tremendous run, despite Westbrook being out. Houston has been killing the Spurs too. Come on now, everyone on this forum who believes the Spurs aren't in trouble are kidding themselves.