The question has been asked if you are hit by a golf ball on a golf course is an Assault.  The short answer is no. The person hitting the golf ball must have acted recklessly or intentionally when they hit the ball.  Just because some hit a bad shot that hit you, that does not constitute an assault.  The courts have held that there is an inadverent risk of harm anytime you play golf or even sitting in the stands of a baseball game. 

In short if you are on a golf course or watching a tournament and get hit by a golf ball, unless they intentionally hit it at you, there is no criminal or civil cause of action. 

The severity of the injury is also not an issue to be considered in determining liability.