The centre-back, who has recovered from a back problem to face Ukraine, said: "Wayne is an integral member of our squad. He is beginning to play consistently well for England and he is improving in the right way.
"I wasn't involved on Saturday (against Slovakia) and had a better look at how individuals are playing and Wayne was probably our best player by a distance at the weekend.
"He was doing the things that the manager asked of him, picking the ball up in dangerous areas and putting people in on goal and getting chances on goal, and he got a couple for himself.
"He is implementing what the manager is trying to get out of team and the more players we have doing that, the better chance we have."
Ferdinand knows it is vital for Rooney and England's other key performers to stay fit if they are to challenge for future glory.
The Manchester United star said: "People say England might have won Euro 2004 had Wayne stayed fit and he played well in the games. There are a lot of ifs and buts.
"But, for the future, it is vital that we keep everyone fit for the qualifying campaign and, if we do that, we will have a much better chance of qualifying.
"The good thing is that when Wayne is confident and playing well, there are not many better sights in football. He is vital and if he is doing the right things, it is only good for us.
"To see that hunger and desire in him to be a better player only bodes well for England's future - and he is still only 23."