I think Sir Alex was also part of the problems that befell Manchester United when he resigned. News then had it that he was the man that handpicked his successor which was David Moyes. That was the genesis of Manchester United problems, an inexperienced coach handling a team like Manchester United at that time, this was a title winning team that was handed over to him.
I totally agree with you on this, even in history, it mostly doesn't end well when an outgoing person handpicks his successor. I once read an article about Ferguson picking Moyes. How could he pick an inexperienced coach to manage a team like that. Moyes has been coaching Everton for almost a decade if not more and ends up mid table, how on earth did he think such a man was suitable for the Manchester United job back then! So I agree with you when you said Ferguson was part of the problem.
Let's take it this way that the problem of Manchester United started when Ferguson hand pick Moyes. What happens then when Moyes was sacked? You and I would agree that Manchester United has brought in many coaches to the team before the present coach Amorim was signed.
My question is, why didn't Manchester United management get the club fix along the line when Moyes left the team for another coach? If I am not forgetting, David Moyes was sack in August 2014 after 10 months as Manchester United coach.
There were up to six coaches that has managed Manchester United before Amorim coming to the limelight as Manchester United head coach. So, Manchester United problem can't be fixed up till date because of the problem Sir. Alex caused in 2013 by hand picking Moyes.
The facts I have started, makes me not to believe that Sir. Alex is still cause of the team lapses because many coach has come and gone out of the team. Pointing Sir. Alex to be cause is bullshit, if Manchester United will not start by selling off their old players, to bring in new ones.