Cuadrado is not the smartest player on the field, he loses his position, gives away ball to easy and it could hurt you if you play him as rb. Also Alex Sandro is built like a mack truck, almost impossible to overpower him. Cuadrado is better dribbler, has higher acceleration, but he is worse than Alex Sandro in almost everything else. Saying all that, it would be very hard to find rb on Alex Sandro level, Darmian is not even close.