I have a friend who was hit in the head (accidentally) by a basketball. She was in her mid-40s. She was off work for a year, and when she came back still had severe headaches and could only work 1-2 hours a day. Less than a year later she started to develop signs of dementia. She can no longer work or even be left alone because she has left her oven on; she has gotten out of her car while it was still in gear, and more; she can't remember where she lives even though she has been there for 20-25 years. She is 47.
Are these likely outcomes for the cheer coach? No. Are they possible? Yes. Would it have happened if that man (not kid), had not done something criminal.
It sucks for him that he hit someone. But it sucks more for her.