He needs to take more risk by taking defenders on, i don't buy the idea he hasn't got enough pace to ghost past people, he needs to at least attempt more take ons and drives either to the barline to cross or cut inside to get a shot away.
The above happening is all down to him and to a greater extant the manager, i remember a memorable quote by Micha Richards saying SAF was yelling at Giggs in the Manchester Derby to take him(Richards) on or he(Giggs) was going to join him on the bench if he wasn't attempting it more often, According to Richards behold it was as if Giggs was 18 again Roling back the year Running at him every time he had the ball.
I do believe wide players need to be encouraged to take their man on, either before the games or in game instructions, because as we all know they are humans and can have the fear of getting whacked but a little encouragement can be the difference in pushing them beyond their limits, for me that's what i think young players like Sancho needs, the task is on ETH to demand that he goes 100mph in games.