When Blake Griffin is your last line of defense, you're in trouble. The Clippers did a nice job of shutting down Tony Parker initially, but Griffin's inability to rotate, protect the rim, rebound, or do anything other than stand around killed the Clippers on the backline. Yes, he's playing at less than full strength with a hurt knee, but the Clippers just can't hang if Griffin offers zero resistance defensively.
Mentally and physically, Chris Paul just isn't himself. Tentativeness and turnovers aren't two things you typically associate with Paul, but the Spurs have crafted a defense that Paul just doesn't know how to crack. With nothing cooking in the pick-and-roll and no easy paths to the rim on his drives, Paul has been taken out of the first two games almost completely.
Eric Bledsoe came back to earth with a few silly turnovers, but he was still the best defender on the court. Although Tim Duncan destroyed DeAndre Jordan on the block, he also did damage by slipping screens and getting into the paint. Bledsoe's ability to fight through screens let the Clippers' big guys stay glued to the roll man -- a huge factor in the Clippers' rare defensive shining moments.
Once again, the ball movement of the Spurs eventually wore down the Clippers defensively. Against a team with one or two offensive options, the Clippers' brand of defense would have been pretty good. Against the Spurs, however, it wasn't good enough. Communication and backline rotations -- two of the Spurs' biggest strengths -- were the undoing of the Clippers' defense.
If Paul and Griffin don't play like stars, San Antonio can go ahead and book a date for the Western Conference finals. The Clippers shot the ball extraordinarily well from the perimeter, but the Spurs limited second chances and won the possession game handily. The Spurs had too much ammunition throughout their whole lineup to get that many extra chances to fire.