The ASTB is just a test, if you can score decent on it the Navy knows they can probably successfully train you to be an aviator. My recruiter said that if you can score at least 5's and OAR around 50 you will be ok.(and she's seen many people selected with 4's and low 40's). After you can meet that they start looking at the whole person concept to see if you are officer material. Granted, if its close competition its probably better to have a higher score to give you an edge, but in the long run its just a screening test, the important part of the application is what makes you you. A test can't tell them that.