We must be watching different players. He is only 19 so I have much hope for him. Right now, though, there are only two dimensions to his game. 1) Dribble until he loses the ball or make a lousy pass. 2) Dribble until he is stopped and pass the ball backwards. It's very rare when he makes a penetrating pass, it's very rare when he makes a great cross, and it's pretty rare when he scores. He absolutely can't pass when he is dribbling at speed. He's young and there is still hope.
If Amad gets some playing time, I would make a large bet that he will look better and be more productive than Garnacho.