Michu has been linked with big-spending Russian duo Zenit St Petersburg and Anzhi Makhachkhala.
Rangel told AS: "Michu is a scorer and these players are the ones who make the difference in a team.
"We have great players but Michu has been our goal man.
"I selfishly hope so (that he will stay). But if he goes to a great club it will be well deserved."