Dropping weight on punches

When you are punching, there is a need to drop your weight in order to be effective. The one punch where this would not apply would be throwing an uppercut because in such an instance you are bringing your weight up with the punch as the punch travels upwards. The other punches cross, hook, overhand (not the jab so much) need the body weight to shift downwards in order to be effective. That is, you lower your body as you punch and drop your weight with the punches. One of the mistakes people make is they stand straight up as they punch and this is a critical error as it actually makes the punch less effective as the body weight is not so much behind the punch as much as it is moving away from the punch.