I've often thought, without having any real inside information, that the "get open" concept is more based on the WR reading what the defense is doing pre-snap and then basing the route off of what he sees rather than having a play with set routes which would be the old school way.
And match-up zone, I think, is essentially "get open" except in reverse. In other words our defense watches film, notes what types of routes are run in certain down and distance situations, and bases coverage off of it.
Is that more or less the case in both scenarios?