Why are these Saints so darn good?

Sorry my first post with a poll so took me a while to build.

My choice is overall Team Unity.

I speak from a Military back ground and when u have guys that will take a bullet for you to get the overall objective completed you operate more effectively and efficiently.
Granted this is Football but I think u see my point.
I liked the Team building exercises they did prior to the season starting. Really helps build a TEAM MORALE vice individualization.