Parker is the only legitimate star on the team at this point. Manu is playing extremely well, but that won't last a whole season and he still makes his usual late game TOs. Tim plays well at times, but gets outmatched at times. So, teams can keep Parker out of the paint and make others beat them. If no one else is ready to play, it spells doom for the Spurs.
I can say this, Houston is beatable, the Spurs obviously weren't into the game on Xmas. OKC is the team that is scary. And if Portland doesn't give in to inexperience, that is a scary team. Indiana is another team like that.
I guess my point is that the Spurs need another consistent offensive star. I was hoping KY would have filled that role this year, but so far has not, but he is their best defender. Unfortunately, that doesn't equate to wins in this league. But it's still pretty early. The problem is that the Spurs aren't exactly a lock for top 4 seeding.