I think there should be more an 'eye of the beholder' view to each player. This is partially covered with the edit player weights.
I would propose each coach acting as a scout also. Each position coach would be able to give their view on players in the position they coach. Co-ordinaters would give their views on either Offensive or Defensive players only and the Head Coach would give his views on every player in the squad (or draft class).
This gives three independent reviews on all players based on what those coaches see as the skills they look for and gives them (the coach) more importance in the game.
Over years you would have coaches that you trust and others that you don't.
I also think that a player should develop differently if he fits the scheme of his coaches. For instance a player who plays DT in a 3-4 base is drafted by a team playing 4-3 base. This should slow his initial development but he would get a boom in year two or three as he adjusts to the new style.
Some players that bust under certain teams/coaches/set ups should/could flourish elsewhere. Occasionally, there should be a player that suddenly 'gets it' and makes a big jump after doing nothing or even going backwards.
Injuries should also have an effect on max potential, especially long injuries in early years.
Obviously, these situations should be outliers as the current system works fine.