I am just to going to say having 15 years of working with both high school and college kids, that a high school pitcher almost always is considered to have a higher ceiling than a college pitcher who has played 3 years.
The acience is much tougher to nail down for high school players though.
Today we should probably see Canada's best highschool arm go. I have had the pleasure of coaching him for the past 3 years. Although there are better arms in college right now, he projects to be better than all of them right now
Pitcher "ceiling" is dependant on several tertiary qualities that have no basis on magically being favoured in a HS pitcher (as opposed to a College pitcher). A pitcher's ability to stay healthy makes up a massive portion of ultimate ceiling (if you don't pitch, it doesn't matter what you can or can't do on the mound). Would you say that Caminiti has a better likelihood of remaining healthy than Yesavage does?
Yesavage has better present stuff and command than Caminiti does. He is more proven by way of dominating higher competition. He obviously has better health indicators by virtue of age and track record. So really your "much higher ceiling" claim is entirely dependent on Caminiti being 17 and projecting consistent growth and improvement year over year, which is entirely possible, but has been proven time and time again to be incredibly spotty and unreliable. Yes, there is a greater than non-zero chance that his stuff keeps ticking up and he ends up being a LHP who sits 96-99 with a plus-plus changeup and a plus breaking ball. But this is a weak/lazy analysis of "ceiling".
Your ultimate conclusion ("a high school pitcher almost always is considered to have a higher ceiling than a college pitcher") is refuted by the actual demographics of the best MLB starting pitchers. If what you said was irrefutably true, then you would expect the best MLB starters to lean heavily towards players who were signed out of HS. This isn't the case at all. If you look at the fWAR leaders so far this season:
1) Garrett Crochet - College
2) Chris Sale - College
3) Tarik Skubal - College
4) Cole Ragans - HS
5) Tanner Houck - College
6) George Kirby - College
7) Christopher sanchez - IFA
8) Logan Webb - HS
9) Tyler Glasnow - HS
10) Ranger Suarez - IFA
11) Sonny Gray - College
12) Zack Wheeler - HS
13) Seth Lugo - College
14) Joe Ryan - College
15) Logan Gilbert - College
16) Erick Fedde - College
17) Corbin Burnes - College
18) Hunter Greene - HS
19) Dylan Cease - HS
20) MacKenzie Gore - HS
7 out of 20 (35%) isn't bad, but it certainly doesn't correlate with "HS pitchers have the highest ceiling". What you'll also find interesting that that many of those College pitchers weren't even "elite" draft picks. Guys like Houck, Kirby, Fedde, Gray were back end or bottom-half 1st rounders, then you have guys like Skubal, Burnes, Ryan, and Lugo who weren't even near the 1st round of their respective draft years. At face value it makes sense to suggest that a HS pitcher has more room for improvement, but in actuality what you often find is that a lot of them regress, while there are College pitchers who actually see consistent improvement in stuff. Tarik Skubal jumped jumped from a 94.5 vFA in his first three MLB seasons to 95.8 last year, and he is at 97.0 this year. So his velocity has spiked at age 26 and 27. And again, he was a 9th round pick out of College.
