The Portuguese winger topped the assists charts in the Premier League last season after providing 18 goals for United, a distinct improvement considering that his total assists in the two prior seasons was less than half that figure.
Nani has also chipped in with nine goals last season, a distinct improvement considering that he struggled to hold down a first-team place when he first joined the club in 2007 and was overshadowed by the mercurial performances of compatriot Cristiano Ronaldo.
Ever since Ronaldo left the club for Real Madrid in 2009, Nani has been improving and stepped up to the plate to deliver for United.
Ferguson was pleased with the way Nani has developed into one of the most consistent players at the club.
He told reporters ahead of their Champions League clash against Benfica: "I think he's always had that potential. Everyone coming to a club from abroad, some can do it quickly but others gradually grow into the club and I think Nani's one of those.
"I think even Cristiano [Ronaldo] took two or three years to get a maturity in his game and that's what we're seeing with Nani now."
Ferguson also remarked how valuable the former Sporting Lisbon man's creativity is to the team, adding: "You see his stats for assists, goals have been fine but his assists are very, very high so he's progressing really well."
Manchester United play Benfica in their penultimate Champions League Group C match at Old Trafford.