As adolescent athletes go through growth spurts and body changes, a structured program helps them to control their body better and understand the changes that their body is going through and that it will  become balanced again. The biggest impact on any athlete's progress is time out of the sport or the game.
Injury prevention exercises build resilience to the demands of your sport, reduce the chance of injury and keep you out on the court, field or track. If you do get injured, a solid base of  strength and fitness gets you back doing what you love, quicker.