Star Trek Voyager - Borg Survivors

In the TNG episodes The best of both worlds 1 and 2 the fleet engages the Borg at Wolf 359 and is almost completley destroyed. Later the Borg cube self distructs. How can there be members of Star Fleet assimilated by the Borg in the Delta Quadrant? There in the episode where Chakoty meets the disconnected Borg, one of them human who was assimilated at Wolf 359.