One other thought: My youngest is now done with the HA college application process, and the family went through it twice in 3 years. I think you have to accept that there is a large element of randomness involved. Baseball actually helps take some of the craziness out of things, because most coaches will tell you straight up that you need X GPA and Y test scores; and if you meet those, they can get Admissions to do a pre-read of your HS transcript to tell you if it's good enough.
If you apply as a non-athlete to an Ivy or similarly selective school, no one can give you similar advice. Perfect grades and test scores may not get you in, while less-than-perfect may do the trick. Much of this is totally beyond your control: Do they have another applicant from your zip code who is slightly better on paper than you, or is the child of an alumnus, or checks some box they want for their class (left-handed oboist who speaks Farsi)? Then this may not be your year. Did they take a kid for this class from your county whose grandparent has a building on campus named after him? There may be no spot for you.
Have your kid talk about his schedule with a guidance counselor and/or a trusted teacher who knows his capabilities, then make the "how many APs" decision as best you can and don't look back. It will not be the factor that determines whether you get into Harvard.