Cubillo gave Duro his chance as coach of Getafe B, before the attacker left for Valencia last summer.
He told AS: "Goals have always come from him. He has a brutal naturalness in front of the goal. He does not make strange shots or shots for the percentages.
"Many of his goals come through the centre and you may think that the goalkeeper is very bad. But that is his gift, as in his day (Ruud) Van Nistelrooy or (Roy) Makaay did.
"When you see forwards like this you think how easy it must be to score a goal. That virtue is very powerful."
Cubillo added: "I like more as a forward, close to the area. But I already tell you that he is very disciplined and generous in the effort. Therefore, he can play on the wing. But his opportunism in the face of the goal ..."
Need a VPN? Or seeking to switch? Then support Tribal Football by clicking here to sign up with our official partners NordVPN. Not only will you receive the best VPN experience, but also great discounts by signing up via Tribal Football. Thanks for your support!