Often you will see someone crouch just prior to a jump. The crouch serves a very specific purpose and that is to stretch the muscles that are going to be used to perform the jump. The benefit of that stretch can be seen by stretching a rubber band and then letting it go. The quicker and longer you stretch the rubber band the further it will go. Our muscles act in the same way. Stretching a muscle just prior to its use will help the muscle create force. In the human body the response of increased force caused by a muscle stretching prior to contraction is call the stretch shorten cycle.
Plyometric training progressively increases the speed and force of a muscle stretch just prior to contraction. The training begins with focus on speed and then slowly progresses with force.
Acceleration uses a variety of plyometric training techniques. Accommodation or getting use to the exercise is very common with plyometrics. So a variety is needed to keep gaining benefits from the work out.
Plyometrics are very safe in general, but as with the rubber band if it is pulled too hard or too fast it will snap. The same holds true with a muscle if it is pulled to hard or fast, it will snap. Acceleration staff is well trained on modifying plyometric exercises for individual athletes to make sure that the exercises are safe and effective.