I wish they were even slightly accurate like you assume, but from just my own anecdotal experience I think it is completely random.
Case in point, I just spent 10 scouting points on the Group Demonstration (the only points I'm spending all season), and of the 19 players that were "rated" 1-2 balls, I have found six 5-ball players (hello, draft options #1-6).
How you spend your points is up to you, but until you've got some information about them, just assume they are random, and the "pretend" rating isn't worth relying on. For what it's worth, in my case, after I list the 5-ball and 4-ball players, I'll be picking some favourite numbers of mine and putting them at the top of my draft order.