Sometimes no amount of practice will lead to something being mastered, the individuals have to be capable of understanding the situations and making the right decisions. I don't think half this group are personally, as a short term fix you'd take that away from them and go back to more of a Nuno style deeper defence where there is no decision to be made, you just sit deep and restrict the space behind regardless.
That goal was just a clusterfuck though. Maybe on another day Toti makes the first challenge and it's all good, everyone else pushes up to meet him but once he's lost the challenge he's got to try and get back in position rather than stand ball watching with his man goal side of him. Kilman should really drop when he's 2v1, it's generally too easy to play the ball through in the gap between stepping away from the runner and getting to the ball carrier. Although tbf he did actually manage it in this case and it was Semedo that played him on with the world's most pointless covering run, if he'd given up instead it would've been offside I think.
There's just no collective thought in the team, either from the coaching or just naturally between the individuals within it. It's like a Sunday league side just turning up an hour before kick off, being told roughly where to stand and seeing how it goes for 90 minutes.