Hey Chico, great topic, my 2020 son is in similar boat about wondering when to start narrowing down interest. Is your son a PO or does he also play another position?
Others on board have much more experience with process, but my read of your son’s case is that school 1 seems solid but schools 2-4 are not offers if they say that he is on short list but they still need/want to see him play again at Fall camp. This might be because they like his velocity so far but want to see better control and/or because his grades/test scores are good but not strong enough to be a shoo in with admissions without using one of their slots so they want to see him perform again to determine whether to give him one of their slots. Is your son’s test scores solidly in the middle or upper end of the freshman class or closer to the bottom 25% of the 25-75% range?
I think it is also fine to let the coaches know who else he is talking to because this may help them make up their minds one way or the other and it’s possible they talk to each other about mutual recruits anyway, but maybe someone else can chime in on this issue.
Good luck!