Most kids I knew in school ended up with broken bones or stitches at some point.
So how close was the boy who threw the ball? And did the target know he was playing or get hit in the back of the head?
We played co-ed dodge ball at maybe the width of a basketball court plus sidelines. Boy jocks with strong arms fifty pounds heavier than picked-last little girl me. They didn’t go easy at anyone, so you learned to dodge for sure. Never saw an injury.