I think Pop took too long to realize Tim was getting old, and he couldn't carry the load on both ends all game, he needed help. That killed the true and tested winning formula we had going at the time. The league also changed. More zone defense (making it more difficult for bigs), more small ball. The Spurs were ill prepared for that. The Spurs also made a bad move in getting RJ, then doubling down on him. That hurt them for at least 2-3 seasons. Pop worked hard revamping the offense, but that hurt the defense.