2 plays come to mind. Line drive absolutely smoked bounces off 3rd baseman shin. E5 was ruling by scorekeeper. Given this SKs kid never played and the guy was toughest SK I've ever seen. Same SK, ball hit in left center gap. Cf dives ball hits the glove and bounces out. E8 was ruling. We were on offense both times.
Seems harsh to take away hits in those cases. It may not be an exact science, but I use ordinary effort based on the agrregate of players I have seen at a particular age. 18U maybe 3b makes that play, 12U maybe not.