The secret to improving change of direction quickness is actually a paradox; what you think is the right thing is actually the complete opposite.
When you ask an athlete to jump as high as they can, most of the time the performance is pretty weak. Minimal effort is put into the jump. The athlete is landing and crashing with a lot of noise at the bottom. The secret to doing any jump is the landing. We want to make sure we bend at the ankle, knee and hip joints to absorb the ground. The muscles absorb the force, NOT the joints. We want to make sure the knees stay in line with the toes and the hips on landing – watch out for knee valgus!
When an athlete trains to land and decelerate correctly, the athlete is training the eccentric phase of the muscle contraction. This is a very important phase when someone is accelerating and then slowing down to re-accelerate. The stronger an athlete becomes in the ability to decelerate (eccentric contraction) the quicker the athlete will become.