The advice (my opinion) is free, but milage will vary... You should never consider the draft out of HS unless your kid is going to receive life changing money. What is life changing money, I guess that depends on your perspective. Figure half the signing bonus goes to taxes and agent's fee (somebody needs to negotiate with the teams). So you get $1M signing bonus, and immediately it's around $500K. The average time it takes a HS player to get a shot at the MLB is 6 or more years, figure a burn rate of about $30K or more per year (training, tools and good nutrition cost way more than the $1,200 before taxes in the minors) and you've got about $250K left after 6 years - that's assuming no large "I got drafted!" spends. Is $250K plus interest life changing if he doesn't beat the odds and make the MLB, when he only has a HS education?
If you have a high achiever academically, (and you're not a top 3 round player) why not leverage that to get a diploma at a school that means something? Is Stanford too much of a stretch, I don't know but if it's my kid I'm going to find out. There's are a ton of opportunity in the Ivy league schools and 90 as a junior should at least open the conversation.
My son was not the academic type, his plan B was to join the Coast Guard if the baseball thing didn't work out. He had no recruiting interest beyond JUCO (he attended their camps / tried out), but he got his AA, transferred to a D1, did one year and then was drafted. I feel he likely got to the MLB in about the same time he would have if he'd had an opportunity out of HS (7 years from HS), except he has an associate degree, a year toward a bachelors, and 3 less years of burn on his signing bonus.