The former Arsenal captain moved to United last summer.
"I’m only interested in players who really want to play for United and who are bad losers, like me," he told L'Equipe.
"Van Persie meets these requirements. He integrated very quickly. With me, there is sometimes an atmosphere in the dressing-room. These periods can be ‘colourful’ when I’m not happy.
"Robin soon realised that I have one idea in mind: to win. He now plays with Ferdinand, Vidic, Evra, Giggs, Scholes, Carrick and these guys. They are the winners.
"This mentality, he breathes it every minute and without doubt should tell himself that he should have signed here much earlier.
"He was spotted by us in Holland when he was 18. We watched a Feyenoord reserve game and he was sent off. Jimmy Ryan, who was watching, said: 'He is a fantastic talent, but he needs to improve his behaviour and control his frustration'.
"We gave up then. We were wrong on this issue, at the time. It happens. It happened. And it will happen again. But the percentage of players we sign who impose themselves is excellent.
"Ryan Giggs scored on his debut for us as a starter at 17."