Ferguson is now strictly hands-off at United.
"I believe in building a football club rather than building a football team," he said.
"I can understand coaches who concentrate on building a football team because it gives them a job.
"It's a results industry.
"You only have to look at Paolo Di Canio last week, five to six games into his first season at Sunderland, they allow him to spend £19 million and then sack him.
"To me, there is no evidence that that is going to bring success."
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