Great teams play bad games against good teams all the time.
Remember how the Celtics got destroyed by the Grizzlies last year? How about the way the Lakers got manhandled by the Cavs? Don't forget that the Spurs blew out the Lakers with ease earlier this season, so this at most makes them even.
The Spurs are so far ahead of everybody else record-wise it's not difficult to imagine why they might be struggling a bit not to have a let down - especially after they totally shellacked the Heat by 30 the other night.
In the playoffs, the Spurs are gonna be just fine. I'm looking forward to a Spurs / Mavs or Spurs / Lakers conference finals.
The Spurs are a deep, disciplined, very talented team. Writing them off because they don't have a 7 footer is just plain silly.