The 32-year-old is said to be unhappy with his playing situation in Spain, and according to the reports, he wishes to leave the country this summer.
United and Paris Saint-Germain are the two sides that are reportedly interested in the Portuguese superstar.
Ferdinand told Goal: "I don't think he really wants to play as a No.9 because he can be tied down there and he can be left a bit isolated.
"He likes being able to come from the wide areas where he gets a little bit of space and that's where he can do his magic. But he used to stand out wide and want to get the ball and take people on. He's not that player no more.
"He wants to get the ball in areas where he can hurt teams and have end product, which is goals or assists, and at the moment there's no better man on the planet doing that."