Pop tried that thing where he subbed everyone out but it did not do much. LaMarcus Aldridge, one game after dropping 39 on the Thunder, scored three. The offense was not even the problem, as the Spurs allowed 39 points in the first quarter.
The defense is struggling, and the Celtics, more than any other team the Spurs have lost to, is just good at executing. The Lakers and Clippers had talent and made plays. These Celts have good players, but just did their stuff better.
Sometimes it just is not your night.
That is always a tough thing to acknowledge, and while the Spurs have been good at not getting dominated, even the best squads — the title winning ones — got blown out. Remember the 2005 team got destroyed in Detroit in back-to-back games? Yeah. It happens.