Former Manchester United boss Alex Ferguson believes that managerial consistency is key if anyone is to come close to replicating the success he had at Old Trafford.
Upon his retirement in 2013, Ferguson was replaced by David Moyes, but the former Everton manager's stint lasted less than 12 months.
Louis Van Gaal subsequently replaced Moyes, guiding United back into the Champions League last term, and Ferguson believes the Dutchman has benefitted from being Moyes' successor rather than his own, insisting there is no proof that a managerial change will lead to success.
"There's no evidence that sacking a manager gives you success. But there is evidence at Manchester United, at Nottingham Forest, at Arsenal that [if] you retain the manager for long periods, you get consistency and you get success," Ferguson told ESPN.
"When you change a coach you change a whole system and that's why I think consistency works.
"It's difficult, I think, replacing a guy who's been there 27 years. In terms of my philosophy and how I did things, all the staff were mine.
"It's better - the second person coming after Alex Ferguson would be better off. David Moyes was unfortunate, it didn't work for him. Good man, good manager.
"And Louis van Gaal has got great experience [at] Barcelona, Bayern Munich, Ajax – he's won the European Cup with Ajax – so he's got experience and of course he's making changes."
One of Ferguson's main rivals over the course of his 1,500 games at the helm at Old Trafford was Arsenal manager Arsene Wenger.
But despite the fiery history between them, Ferguson believes that Wenger has been correct to stand by his philosophy in recent years, and that the club have been right to stick with the Frenchman.
"It's just like me if I hadn't progressed the club after the '94 team or the '99 team I would maybe having the same problems as Arsene, but he's stayed with his conviction and with what he believes in," he added.
"But who are they going to get to replace Arsene Wenger? Who are they going to get who is better than Arsene Wenger? And that's why they don't [sack him], that's why they've stuck by him."
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