Personally, i see no problem with over signing. its a good way to cut dead weight. Recruiting classes are hit and miss, you will have some boom and you will have some bust. No need to have an unproductive player on your roster for four years when you can bring in someone from JUCO or an All American Freshman who can make more of an impact. As far as academic side of it, if they don't qualify, grey shirt them and allow them to come in the following semester and if they don't qualify that will be one less worry about numbers. If they do qualify you will have time to evaluate the players already on your roster and if one or some are not cutting it, you give them their walking papers and replace them with the grey shirt player or players in the next recruiting class. Its a good way to keep STUDS coming in and JAGS going out, all while not going over the limit.
I don't think the high school coaches Bama recruits come from care too much if their former player is cut for lack of production. They understand that Bama is loaded with talent and Saban is one of the best College coaches in America and if their former player can't cut it at Bama then they do not belong there. Also, unlike Miami, Alabama doesn't have people like Manny Navarro and The Miami Herald giving high school coaches, parents, and former players a platform to bash the program. In Miami, the high school coaches are different. See the Ice Harris/Denver Kirkland situation. All in all, you can say over signing is unethical but at the end of the day college football is a business.