Yes soccer is up there because of the "heading" correct term? Some say kids shouldn't do it at all - some say it is because of this parent coaching - the parents don't know the correct way of doing it so it results in more injuries. Some say it is better for the kids to learn the correct way of doing so when they join more competitive leagues that "head" the ball, they will know how to do this correctly without injury.
Now I am glad about my girls not being interested in soccer.
I haven't heard that baseball or softball is near the top - my concern now with softball is the teeth. We have seen/heard of couple of severe mouth injuries in softball. I'd imagine it would be similar with baseball - my younger daughter wears a guard - I think it is more an issue with younger players as their reactions and skill level is so much lower and more play closer while in the in-field. All it takes is one line drive and there go the pretty little girls permanent front teeth.
My daughter's dentist also said when she heard my daughter plays softball - she has to wear a face guard.
Basketball is up there - I believe for some reason girl's basketball is higher. I've personally known one girl who was out of school and of course basketball for months because of this - and she is a big girl. And it only gets more intense as they get older.
I think both parents and coaches need to be aware of the signs.