These settings allow you to control how you want to deal with individual players as they pick up fouls. The engine will automatically determine whether to take a player out or leave him in based on the number of personal fouls, time remaining, position on the depth chart, and game score. This is considered 'normal' substitution logic.
You may also choose to set a player to be dealt with 'more aggressively' or 'less aggressively'. If you choose more aggressive, then you're telling the engine that you're willing to leave the player on the court longer than normal and vice-versa for the less aggressive option.