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.
Even though Sir Alex Ferguson handpicked David Moyes as Manchester United head coach to compensate David Moyes for failing to pick David Moyes as his assistant coach at Manchester United, I will not blame Sir Alex Ferguson for the problems that befell Manchester United because David Moyes was doing a good job at Everton, and he has been in the Premier League for years, and Sir Alex Ferguson believed David Moyes would be able to continue his legacy at Manchester United, but he didn't know that David Moyes couldn't handle Manchester United.