Look at it like this:
Popovich is Parcells - relying on older, slower, more experienced players because for whatever reason he doesn't trust younger, quicker athletic players. He's built his trademark around defense. Ironically, it is now the DEFENSE (a strategy that he built) and those players that he chose that are now failing him. His system is flawed because he no longer has the players to make it work. He failed to supplement the talent level by integrating some youth and athleticism.
Avery, on the other hand, is Sean Payton. AJ is a disciple of the Pop system. Knows it well. Studies his mentor's squad and knows exactly where they are vulnerable. It is AJ, much like Payton, who is smart enough and cunning enough to know how, when and where to exploit his former team. He's made the right player moves and like Payton, he's instilled a mental toughness and hunger in his squad. They attack, attack and attack.
It's clear, the student has now pimped the teacher. This time it's happened with the Spurs - not the Cowboys.