In my eyes it all goes wrong with the game plan.
You would never get anything out by attacking the wingback from outside if the opposite sits in 541. Even if you get to the byline, the cross can be easily blocked.
Better to attack the space between the wingback and CB. That is the weak link. The only good chance in the first half came from there. Alvarez set piece goal came from there as well. But in the majority of the match we just heavily focused on the left channel trying to beat their WB from outside. We did not put enough pressure in the half space. The ball rarely reached there. Nah...
It just exposed our weakness in the squad. We don't have a recognizable left full back. If there was one holding the width, we can have Doku attacking the half space between WB and CB (or if it is not his thing, Jack maybe).
I never really understand Pep's obsession with wingers holding the width and (almost) never let them dribble/attack directly in the half space like every other teams in the PL do.