What would pull the trigger for an offer?
What does your son have that sets him apart from the hundreds of other players a coach has seen? Could be a lot of differently things. How the pitcher prepares in the bullpen. How that players teammates act toward him. How patient is the hitter at the plate. Is he a lefty? Does he run fast? Just an example, of what I think might make the coach make an offer.
It's not all about the things that are noticeable. You can tell how interested a coach is by how many times he shows up to watch.
Definitely coaches dont want their guys facing someone they feel will be an impact player.
JMO