From a clinic given at the University of Florida comes some great notes from Butler's Brad Stevens talking about the Bulldogs' defensive principles.
Here is Part IV of those clinic notes:
The first important question for Coach Stevens in regard is "where are you on the floor?"
1. If you have an athletic advantage, you can pressure more.
2. If you are at an athletic disadvantage, you have to trick the offensive player in different ways to keep him off balance.
3. Butler plays a lot of 1 on 1...post and perimeter. Everyone must be able to guard two dribbles on the perimeter. This includes post players because they might switch onto a guard late in the shot clock.
Next: Defensive DNA #4: Closeouts