why would he be backup to Darmian? because he didnt cost 13million? bullshit, its easy to see that he's better talent than him, needs work on his first touch and balance in attacking/defensive positioning, sometimes he's too aggressive but Rafael was also like that and he became a great defender after playing decent amount of games. Darmian is just shocking going forward, lacks any kind of speed, you can say that he is defensively quite sound but he was skinned many times as well like against Arsenal. I dont see any reason why the Italian should start ahead of Varela, modern fullbacks should be able to overlap and have good ability on the ball. Also Varela seemed very good defensively for U21, just needs to adjust his game to higher tempo in intensity in the premier league and he will come good. Darmian is just average player and Tony V is halfway gone bt wouldnt mind him as RB backup for a while, not sure as winger, Pereira coud do well there as false winger, certainly has better mobility than Mata who is a similar player but slower and less mobile than him..