Michu struck twice in victory at Arsenal on Saturday.
Rangel said: "I think he (Michu) could play for a top four team.
"It's probably a bit crazy to say it, but I think he has proved himself in the first 15 games of the season. Scoring 10 goals in 15 games of the season is not easy, let's hope we can keep hold of him.
"He is really happy here and maybe the club will have to give him a new contract, but that is not for me to say.
"He is surrounded by nice people, there are lots of Spaniards here who he gets on very well with and he loves it at Swansea."