The one thing you don't do vs City is play a high defensive line with big gaps between the defence and the midfield. So what do Schalke do? Play a high line with massive gaps and mountains of space for a rapid Sane and a rapid Sterling to get a ball to run onto. No wonder they are losing 5-0. You'd expect that because they are going gung-ho to get a couple goals but they've been miserable. Then when Sane has gotten the ball wide, nobody has thought to mark anybody in the box to stop them having loads of time to get a strike away.
Horrific defence, up there with the worst I have seen this season.