Ferdinand said: "The more characters there are in the Premier League the better and Roy falls into that category.
"He speaks his mind. He did it as a player and was doing it as a manager. There has been a lot of talk about him, with people saying he was going to leave. Even so, I was a bit surprised.
"Roy is his own man and he will make his own mind up.
"I am sure Sunderland will move on because he has been there and I am sure he will move on himself."