A study in Ergonomics found that, among soccer players, high performers in the vertical jump use a more hip-dominant strategy than low performers.
The difference was 4.3 inches!
Differences of joint movements at the knee were not found between the groups, suggesting that the hips were the big difference-maker.
When descending, load the hips by sitting back.
This allows you to more effectively use the large, powerful muscles of the hips as you explode into your jump.