Ferdinand has been written off many times during the past three and a half years, firstly after the extent of his back problems first became evident. This season, though, Ferdinand has excelled and, although the 33-year-old has missed games, the most he has sat out on the trot has been three.
"I keep thinking I signed Rio three or four years ago," said Ferguson ahead of Monday night's Premier League encounter with Fulham at Old Trafford. "I forget he's been here for almost 10 years now. He has taken on that role of the influential person in the dressing room. He is great with the players."
He added: "If you can keep players long enough for their influence to spread - and in the modern game it's difficult to keep players for five or six years - they can take over from the older players as they disappear."
It is why the loss of Gary Neville did not have the negative impact many imagined and why United should continue to challenge for top honours even when Ryan Giggs and Paul Scholes, again, eventually call it a day.
Should United retain the Premier League, it would be Ferdinand's sixth, which would leave him only two behind Alan Hansen, who antagonised Ferguson earlier this season when he claimed this was the worst Red Devils outfit he could remember.
And for all his back issues - and recent reports he may be interested in a lucrative move to China - Ferguson is convinced Ferdinand will carry on for a while yet.
"He is still young for a centre back," said the United boss. "In normal terms you would expect a centre back with his athleticism to play well into their thirties anyway.
"We all know about his back problem, so we've had to manage that. He has adapted really well to the challenge of making sure he is fit and fresh to play in the games when we need him.
"How long he goes on for is all down to how he feels physically, other than that he has no issues at all."