In Norway, we have a rule that the center-back who is on the ball side sets the offside line. I would assume this is also the case in England when playing zone defense. Anyway, Solbakken (the Norwegian national team manager) had a chat with Guerdiola after a match, and asked how Guerdiola solved it. Guerdiola said the following: Alves looks at Pique, Pique looks at Puyol, and Puyol looks at Abidal, and they solve it somehow.
Now zone defense is something that has been used for a long time in Norway, imported from England, but outside of Scandinavia and the UK, this is a relatively new phenomenon. Rangnick was e.g. ridiculed around the 2000s for promoting zone defense in Germany. Many coaches, at least from countries that are used to using zone defense, have had problems when implementing this in other countries where there is no culture for this. Many have struggled defensively, and been fired.
Among others Solbakken in Cologne and Wolves. He failed to teach the players zone defense, and he said that Norwegian 12-year-olds were better tactically trained than professional football players in these clubs. Later he has had success with Copenhagen, but there they were far more adaptable.
Zone defense is now starting to become quite widespread, and now the biggest controversy is zone defense on dead balls. Guerdiola and many other top coaches use it.
Anyway, when I see Keane play football, and I see that he constantly uses the ball and opponent as the only reference, I know it's a long uphill. The same can be said about the rest of the Benny Hill gang behind there. However, they will learn it, but for some, such as at school, it takes a little longer.