Why did the court find that a battery was alleged, but not an assault?

A middle school football player, who was injured when football coach thrust his arms around player's body, lifted him off his feet, and slammed him to the ground while explaining proper tackling technique, brought an action for negligence, assault, and battery claims against the coach. The court held that player who alleged that he consented to physical contact with players of like age and experience, but that he did not expect or consent to his participation in aggressive contact tackling by adult football coaches stated cause of action for the tort of battery.