I’ve seen a number of articles about how dangerous sports like baseball are -especially for youngsters. Apparently batters get hit on the body and head frequently.
Obviously, helmets and body armour are a good idea, but they are restrictive when you are trying to perfect technique -so today’s invention offers an additional/alternative layer of safety for trainee players.
There are some very high-accuracy ball tracking systems around.
I suggest using one of these eg at a training school to detect ball motion toward the helmet of a batter (or batsman).
If a potential collision were detected, it would be reasonably straightforward to fire a spring-loaded plate up off the ground to shield the player from the impact.