Ferguson told ESPN: “He had an improvement in terms of his timing and movement in the penalty box. His positioning also improved from the previous season.
“He got us over 30 goals and if he does that again and adds a little bit to his game then that is what we expect.
“The boy has got an incredible armoury of talent and what we have to do is to wait for that maturity.
“We also do nurture it and try to advise and coach in a fashion which will improve his game. But the most important thing I think he needs now is maturity and, when he gets that, I think you will see the complete footballer.”
After England’s disappointing World Cup campaign, Ferguson reiterated calls for a winter break in the Premier League schedule.
He said: “The FA has to give the country the best possible chance of doing well in the World Cup.
“Because of the nature of our game and because of the demands from television to have a programme every week, I have been talking about a winter break but nothing has happened.
“They must realise that, going into the World Cup, they have handicapped their team.”