The pair have already netted 14 goals between them this season but Ferdinand suggests they need to sustain that scoring form to be classed as a top quality twosome.
"In this country and in football in general I think we build people up too quickly," Ferdinand told BT Sport.
"That's not to say they're not a great partnership - they're proven at the moment. They're on top of their game and they're playing very, very well. They've scored some great goals.
"But I think you judge partnerships over a period of time. Look at [Dwight] Yorke and [Andy] Cole, [Teddy] Sheringham and [Alan] Shearer.
"These types of partnerships aren't developed overnight over a course of part of a season, it's over a period of time. So I think it's better to give these people time."
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