The Spaniard has had limited funds to work with during the current window, but Benitez was able to make his sixth signing of the summer earlier this week with the addition of the 27-year-old from the Potters.
"We knew him when he was in the academy at Real Madrid and he was the top scorer. He was doing well," said Benitez, according to the Daily Mail.
"Obviously, in Spain, when he was at Deportivo La Coruna, we had some information, and when he was in Germany. We know the player and we know he has the potential. Was he playing at his level at Stoke? Maybe not. And can he do it here? Maybe he will have more chances.
"It's easier for me to talk to him in Spanish than maybe it is for Mark Hughes, so then if I have to transmit something, maybe I can do it. But then after that it depends on him. I can explain things, but it depends on him."
Newcastle face their second game of the new season when they travel to Huddersfield Town on Sunday.