The former Manchester United centre-back does not think the striker's current position in Louis van Gaal's side is his best.
The former team-mate of Rooney's - both at club and international level - says he was surprised when the striker told him he wants to become an attacking midfielder instead of an out-and-out striker.
To Ferdinand's mind, Rooney was one of the best forwards in the world and he doesn't think he should be playing in behind two strikers.
United boss Louis van Gaal has used him there this season - and is not the first to have done so.
But, writing in his new book '2 sides,' Ferdinand says playing further forward is Rooney's best position:
"He was top scorer in 2012, scored a hatful of goals up front on his own, as the number nine, which I think is his best position," the 35-year-old mused.
"The following year he says 'I want to play number ten. I prefer it. I'm better an number 10.' I said to him 'you've just had your best year statistically and in terms of adulation and the media loving you. Why do you want to play ten??'
"He was just below the two best players in the world. He was just below [Lionel] Messi and [Cristiano] Ronaldo and I thought he could go on and improve and maybe join them."