Yup. As it looks there (can't ever get the whole picture from a still shot) it seems to me like everyone has a man but Mustafi. He's just hanging in space. He needed to come across much quicker to Vardy(as Gab was gesturing for him to do) so Gab could right away take the runner who blew past Xhaka. If we are just in a regular four then Mustafi is already on Vardy, Gab is on the other guy and Xhaka is higher up in midfield helping to press.