SplendidSplinter, if the school is your son's top choice, I would encourage you to contact the head coach via email and write him seomething like this:
Dear Coach Smith,
My son John greatly enjoyed visiting with you and your staff in November and is excited about the prospect of playing for your program. While this is great news, I will admit that I have concerns about your asking him to hold off on committing to another program since you did not make him an offer yourself.
From my limited perspective, it seems as if he is your second or third choice and you are waiting to see if your first choice prospect commits. If this is the case, I would appreciate your filling us in on a timeline that will better help us know what to expect (i.e., a deadline you have given your top prospect or your plan for moving on to your next choice if your top prospect ends up committing elsewhere).
Cranford University is my son's top choice, but I don't want him to squander other opportunities to play if he will ultimately not end up getting an offer from you. I would appreciate any insight you can provide that will help us in assessing the situation and making a decision.
Respectfully,
Mike/Brenda Jones