College pitcher drafted at 20 with a full season and the half season (in which he was drafted under his belt).
Control VL and VR in the low 70s. Pitches 70/60/40/40.

how much more can you expect to see from this guy. 2-3 more seasons of development. Does he end up a stud or not quite get there?

Take the first ratings you have of him. Take the first year of growth. Multiply that growth X 2. Add that number to your first number. That is what he will be.

He's not mine.

Then you're screwed. Supposedly advance scouting will help but I still hear people with $20 million getting fuzzy ratings.

Trust me. $20 million is like 80%. I'm gonna start backing them down to zero.

There's some variability here-- but for about 80% of these guys, they have:
6-10 points left to grow in control and splits
4-8 points left in pitches and GB/FB.

Almost never more than that, and about 15-20% of the time they have less.

Remember that the current owner can see the development pattern, and knows if this is one of the bottom 15-20%.

What position was he drafted, low first, high first, supp, later? What's the owner's track record of drafting college players?

Top five pick. Owner was in second season in league. Fwiw I scouted college max that year and didn't see him as a top 5 pick.

I don't remember my projections for him I just remember that there were three or four pitchers I ranked up top and he was not one.

Save your projections in excel for situations like this. My WAG, based on his current ratings, is your original assessment is probably fairly accurate and he doesn't quite get there.