He's a solid choice, and helps to balance the side without leaving Cash (or whoever is at Right Back) with all the work to do. I think he's doing what he's told, and we've currently got Rogers as the plyer who's allowed to lose the ball, and sometimes Sancho/Buendia. But Emery is playing very safety first football. It wouldn't surprise me in the least if Emery has said he's allowed to beat his man, but should only attempt it if it will have a 99% chance of coming off.