Lectures about concussions in youth football tend to be a dull compound of science and moralizing. So instead of words, let’s try a picture. Pick up a bobblehead and shake it — hard. Watch the little spring neck whiplash back and forth and hear the toy rattle, and imagine your son’s 7-year-old brain inside the shell. That’s why you need to hand him a flag instead of a helmet. But if you still aren’t convinced, then look at it this way: What was good enough for those Manning boys ought to be good enough for yours.