Proud praent,
As long as they stay injury free, I will say all of them. Let's look at Connor Eason since JB was throwing 90-91 as a frosh. Connor was 5-10ish and 81-83 as a frosh but the ball came out of his hand very easily. UVA saw him throw several times and liked him but wanted to see more growth. So...they see him this past winter at the East Coast Baseball camp where he had grown to 6-1ish and was touching 85-87. He committed this spring. Just last week at the PG National, he touched 89 as a rising junior.
Will there be others who throw harder by the time he matriculates to UVa? Maybe, maybe not. What Connor has shown them is the ability to get high level hitters out (with the EvoCanes) and a consistent pattern of velocity improvement. They can project him to be throwing 90+.
Ilovebaseball,
I'd suggest your son find a solid travel team so the colleges of interest in him can see him play. They won't recruit him off any All District teams.