I'm not sure on the potential. There are 12 potential levels, and 5 potential ratings. They could have split the potential levels 3:3:2:2:2 or 2:2:2:3:3 or even
2.4:2.4:2.4:2.4:2.4. My draft pick last seasons did not have a potential rating.
IIRC, there are 25% of players are all star or above, so a 2:2:2:3:3 system would mean 4 and 5 would correspond to all star or above or 25% of players. There are a lot fewer players with high potentials than those with high star ratings.
I'm not really sure on the box scores. They could be synthesized based on the ratings, which would mean that your interpretation is correct. Though how does a 3-3 FT shooter compare against a 12-14 FT shooter?
Or they could be simulated, where that is the report from one game. Look at some of your players' game stats and see if you can figure out where they are more skilled. And then do it from the season totals. The season totals will give you a much better estimate.
Last season, I seem to recall some players having really low minutes in the box scores (10 minutes), so it might have been adjusted. Some of the players couldn't be 5's based on the game in their box score, so I kind of lean to the simulation version. There has always been the Star Rating and the Grade Rating, but before last season, there was no Potential or Box Scores. There was a best stat, which would tell you that FT or ID was a player's best stat. Potential did not exist at all until the time of the draft last season - that was our first experience with it.
The Age is new for this year's draft.