Since taking over the club in 2005, the Glazers have spent £696m on interest fees, bank charges and debt repayment but only £382m on players, per The Guardian. Every week they spend more than £400,000 on interest on the debt, equivalent to the salary of two or three more world class players.
United are the most profitable club in the country, one of the most profitable in the world, yet their net spend over the past five years is closer to Stoke's than it is to Chelsea or Manchester City's.
All of United's failings begin and end with the Glazer family, who were lucky enough to have the greatest manager of all time in charge of the club for the first eight years of their ownership. Ferguson was able to bridge the gap most seasons but every time United lost out on the league title since 2005, it was to a club that had spent considerably more than them.
Ferguson did what he could on a much smaller budget than United's title rivals, but it seems as though the Glazers are just beginning to work out how much money the former manager saved them. There's no excuse for one of the richest clubs in the world not being able to compete for players in the transfer market, but that is exactly the position United find themselves in thanks to the Glazers.
Even the appointment of Moyes, a manager who would be happy with any transfer funds he was given as opposed to a world class manager who is used to spending, is a decision made for financial reasons not what was the best move for the club.