We don't appear to be watching the same game, or you still can't count.
There were two binners in the six yard box, and three outside... making five, not four.
You mark those who you perceive as a threat, as was done.
"they were sticking too rigidly to a zonal marking plan"
that is utter nonsense ! ! !
as the three players just outside the six yard box move with their marked men - the whole idea of zonal marking is you mark a zone, not the man
this was seen in the following corner where the defenders took up different positions as they sought to mark attacking players, being the ones they saw as the threat
zonal marking is akin to placing all the fielders in a cricket match in equidistant to each other on the basis that they will cover a certain amount of the boundary