There are 5 potential levels above AllStar, so each potential rating for the draft probably corresponsd to 2 or 3 potential levels.
It would make sense that each potential level corresponds to one level higher for the skill cap. And I could see a 4 potential including "allstar" so that a 3 potential is "star" or less.
So pick #1 and hope he is 18. With 80 teams in Macedonia, the potential might be enough to eventually get him on the All Star Team.