Pirate Fan is right, your son still has to "tryout" in order to make the team. Your son may have looked great during his showcase, camp, high school game, but once he is on that campus, in the college environment, things can and do change.
Your son has to work his tail-off during the summer, prior to college, and then again in the fall when tryouts occur. There are no guarantees!!!! I watched kids that I thought were decent ballplayers get cut! They were either sophomores or juniors. Your son still has to prepare and perform. Nothing should be taken for granted. That's why I laugh when I here about kids that I know who are at D1 schools, and are either not playing, starting, or whatever. I'm not try to be mean in my statement, but these kids had abetter chance of getting a better education from a smaller D3 school, plus stand a better chance of playing right away, and even saying this, there are still no guarantees!!!!!
Every high school player dreams of playing at a big D1 school, an ACC, SEC, Big 12, etc., school, or even being scouted for the pros from high school like a kid from our area was this past June. This is very, very rare. Have your son give himself the opportunity to play, if that is what really matters. Don't let him say to his friends that "I'm on this D1 schools team," when in reality he may be on the bench for a very, very long time!!!!
Do what's best for your son and get the great education that is needed for the future, and also have some fun playing baseball!!! JMHO