Phanatic, this may be something you already are well aware of, but... These days, admission to top-tier academic schools is radically different than when those of us with HS-age kids were applying. Your son may have straight As and a 99th percentile ACT, but I do not exaggerate when I say that may not gain admission at any of the schools discussed in this thread. Williams and Haverford, for instance, both have ACT means of ~33. That is high 98th to low 99th percentile. They turn down many kids with phenomenal transcripts and test scores, That is why a coach's 'tip' for recruited athletes at a HA D3 is so valuable--it means a kid who has the academic credentials for admission gets in, rather than having a 10% or 20% chance.
Ultimately your son should choose the right school for him based on many factors, of course, not just baseball. But I would not assume he will be admitted as a non-athlete ED applicant at very HA schools (unless there is s building named after your family on campus). You need a Plan B. And Plans C and D, possibly more. I say this as someone who saw one of their kids with a 3.9, a 34 ACT, multiple varsity sports, etc. get turned down at the majority of HA schools applied to (although things turned out OK, as they almost always do for good students who cast a fairly wide net).