Pressure defense is about making players uncomfortable with the ball. Philosophically, an offense is about creating separation and defense about preventing separation.
Using "Advantage-disadvantage" can help defenses cope with scrambling. It starts with maximizing ball pressure, with defenders 'attacking' the ball. The defense commits to pressure and keeping the ball out of the paint. The best man-to-man defense resembles zone off the ball and the best zones resemble man-to-man on the ball.
With 5-on-4 the defense protects the paint.
The ball goes to the wing and defense moves on the pass. X1 drops to the level of the ball. X1 and X3 are both in the paint.
In the corner, the four defenders become a box. Note the "helpside I" alignment. As the defensive rotation improves, the offense goes "live". For convenience in the drill, this happens with ball reversal to 3 via perimeter or skip passes.
Successful defense begins with establishing the proper mentality.