Loose hamstrings and buttocks allow you to transfer your weight correctly on the backswing and downswing for maximum power
The roll of the right leg in the swing is very misunderstood in golf, it is extremely important for control and distance, as the club comes into impact the right knee, foot and ankle roll in and at the finish the right thigh should catch up with your left thigh
Develop control and feel for pitching distance by creating a set position on the backswing as your benchmark and then vary your shot distance by the power you swing with