Martinez is naturally delighted the forward decided the best place to develop his promising career is under his guidance at Goodison Park.
"You have to keep checking that he is only 19 because he is an incredible footballer," explained Martinez to evertontv.
"Yes, he is very young and needs to develop but what has pleased me more than anything is that he had so many offers to join different football clubs and he has chosen Everton.
"He has told me that the history and knowledge of the fans for good football will help him, as well as working with a group of players that he knows have got incredible experience that he can learn from.
"He is an electric footballer, exciting to watch in one-versus-one situations and he can be described as an old type of winger that the modern game needs.
"Again, I'm really excited to bring him to the football club."