It appears that your lefty pitcher has performed well in front of the right people. Impatience, frustration, worry all set in when the phone/texts/e-mails are not as plentiful as you'd like after seeing him do so well.
My son was playing for a top level west coast travel ball team the summer before junior year. He absolutely went off at the travel team's prospect camp, which had over 30 college coaches (mainly D1) attending. Hit a ball out of a minor league stadium and hit the fence on two other of the many hits he had that weekend. He ran a sub 7 60yd and had a good arm, 3.9 GPA. Offers after that event??? Zero! It took until the following summer as a rising Senior for offers to come in. He will be attending a fantastic university next year, which is a great fit baseball-wise and academically...it worked out.
Your son will get offers and go where he is supposed to. Funny thing that I have seen from my son's teammates that have put in the work - The moon and stars typically align and the college thing works out. Good luck and keep supporting him, he'll be fine!