The Brazilian made a big impact after joining Manchester United in 2008, large enough to get him a place on the bench for the following year's Champions League final defeat to Barcelona.
Yet a red card in the 2010 quarter-final defeat to Bayern Munich highlighted there were flaws in Rafael's game that needed to be sorted out.
As Ferguson pointed out, he has reinforced the point on a number of occasions since.
Indeed, there have been times when it seemed the message was not getting home.
However, during United's chronic early-season defensive injury problems, Rafael has been one of the stand-out performers.
The 22-year-old has already scored twice this season and Ferguson claimed he was man of the match against Stoke on Saturday.
And, though the impending returns of Chris Smalling and Phil Jones will apply more pressure on the right-back berth, Ferguson believes Rafael's massive potential is now being realised.
"He is maturing and learning all the time," said Ferguson.
"Rafael has all the ingredients of a great player.
"He is blessed with great enthusiasm, skill and speed.
"He was quite impulsive and tended to over-commit himself.
"We have gone over it a few times but, bit by bit, it is all coming together and he was easily our best player Saturday."
Rafael's growing maturity shines through in the manner he accepts Ferguson's criticism but there are still issues to be resolved.
A disastrous mistake in the opening seconds of Brazil's Olympic final defeat to Mexico has probably contributed to him not being selected in any senior internationals since he made his debut in May.
With the World Cup set to be held in the most football mad nation on earth in 2014, Rafael has an additional incentive to maintain present progress though.
And he does feel people are starting to assess him in a slightly different manner.
"I do think they look at me differently now," he said.
"They way I play for United has changed a little bit and I have scored some goals as well.
"But mature is the word. I always want the ball. Now I read the game more and know what the opposing player is going to do.
"It is a big time for me. The World Cup is the big competition for Brazil and all the fans expect us to win.
"I am really looking forward to being there."