I feel sorry for our defence at the moment, I think the poor system that our manager has us playing is making it very difficult indeed for our defenders (especially our centre halves)
The opposition deployed a true winger on each side of the pitch, this gave them two big advantages, firstly it kept our two full backs largely pinned back ensuring that (as usual) we had no width on either side of the pitch when attacking. Secondly it meant our fullbacks had to take a wide defensive position, leaving our two centre halves having to cover far too much space and creating ample opportunity to thread balls in behind them. Bony was then able to exploit that large gap between Fazio and Vertonghen over and over again. I thought as the second half went on Davies seemed to operate a bit narrower which closed off the space for passes to be slid in behind us for Bony, but it gave Routledge the run of the park down the right.
The best way for us to have countered Swansea's system (and it was the way we also should've countered Palace as well) is to play a pacy, winger ourselves. This poses the opposition a question over whether to allow our pacy wide player to go one on one against their fullback or (as is often the case) ensure their winger plays deeper to help their full back defensively. That in turn would allow one of our fullbacks to tuck in and close the space off for the passes in behind us for the centre forward.
Currently teams do not need to worry about their wingers having to help out defensively against us as both of our 'wide' players always take the ball back infield to where the opposition have their defensive numbers. Perhaps it would help if our right sided player did something other than constantly lose the ball, but right now it looks to me as though any half decent manager knows the system that we will play and knows exactly how to exploit it.