Two plays from Sunday's win perfectly illustrate the growth of the defense.
Early in the season, the defense had issues with its fundamentals. Eyes in the wrong places. Assignments busted. Players trying to do too much. Any of those three things will cause issues on their own. When they're all prevalent, which was the case for the Saints earlier this year, it can cause people to question the group's ability to perform as expected.
New Orleans' biggest issue early this season was wandering eyes. You'd see it in coverage and against running plays, where players would get caught watching the backfield or some motion or shift. Once the smoke cleared, the mirror's reflection was often of a player running free with the ball in his hands.
Despite being without several key players, San Francisco offered a great test because of all the ways they go about scheming things open. The 49ers used motion on 30 plays on Sunday. So, if the Saints weren't on point, it wouldn't have mattered who they were playing. They would have found a way to beat themselves.
New Orleans was on point.