To answer the OP's original question, without regard to baseball and just looking at college admissions, most admissions counselors would tell you to have your son take some classes that challenge him. If he is getting all high As in honors classes, he should pick a few AP classes to take. That's what rigor means. It sounds like an honors class is not rigorous enough for your son. That doesn't mean he should overload himself with AP classes. Try to find a balance. What are his strongest subjects? What is he most interested in? Pick a couple of those classes to go the AP route.
There's a lot of good and not so good information on this thread about college admissions and what colleges look for in an applicant's grades. Every school is going to be slightly different in its process, but most smaller (and some bigger, more selective) schools use a form of holistic review, looking at the kid from lots of different angles.
Part of that review is to compare the student's choice of classes and resulting grades against those of his peers at his own high school. The guidance counselor at your high school will usually send some sort of school profile that contains a lot of background facts and data about the school, including demographics, clubs and sports, special programs, etc. It will also include how many AP and honors classes they offer, how many students take them, how many get a passing grade on the AP exam, what is the middle 50%, top 20%, 10%, and 1% for GPA and SAT/ACT test scores, and how many National Merit Scholar semi-finalist and finalists they have.
So if your son's high school offers 25 AP classes, and the upper half of the class usually takes between 6 and 7, and your son has taken only 1, but has gotten As in honors and on-level classes, the admissions counselor will probably come to the conclusion that your son is bright but doesn't push himself very much. And, he is not going to compare as well as another kid attending a school with a similar school profile who maybe doesn't have as high an unweighted GPA, but has taken 6 or 7 (or more) AP classes.
Many high schools post their school profile on their website, if you'd like to see what the college admissions counselors are looking at to evaluate your son's rigor, I would start there. If they don't post it, you can make an appointment with your son's guidance counselor and see if you can get a copy. Guidance counselors often also write a letter about your son to the college admissions office describing your son to them. They will often try to put the student in the context of the high school student body as a whole. Does he stand out in any way? Does he excel and if so how? This is how guidance counselors help college admissions counselors, who try to know about the schools in their region, but can't know about all of them. So, it would be a good idea to encourage your son to get to know his guidance counselor. If they actually know him when they write that letter, they can put a lot more real information about him (leadership ability, personality, strong character traits, etc.) in it.
Couple of things I think are not necessarily true, at least as blanket statements. Honors classes also count toward rigor and will be relevant to a college admissions counselor. Many colleges don't give honors classes as much weight as AP classes in their consideration of rigor because not all honors classes are equal. One school district's idea of an honors class could be very different than another's. AP on the other hand is at least theoretically taught to a particular standard set by the College Board. That is why college admissions counselors will give them more consideration than an honors class. And while some more-selective private schools (not all but some) won't give college credit for them, they will look at whether your son took them, what grade he got in them, and whether he got a 4 or a 5 on the exam when evaluating the rigor of his high school curriculum.
Also, how a particular college handles the weight high schools attach to honors and AP classes will differ and you will need to check with each college your son is considering to know what they do in making an admissions decision. But, many selective colleges DO care about and like weighted GPAs. That's because they can report them to US News and World Report and help their ranking.