I've always found that aggressive balls tend to start off as poor feeders--they're too defensive, and want to kill the rats with their teeth instead of constricting and eating them. <lol>
My experience has been the opposite. The babies that are most aggressive are the first to take their first meals out of the clutch and continue to pound food, while becoming more docile as they put on weight (gaining size, means less likely to be a prey item).