I blame ATC and Management! :-)
So, Northwest had a perfectly good crew scheduling system and DELTA had to change it...and they didn't provide ground school in how to use it.
And ATC took over an our to figure out to use the last frequency that this flight responded on. Now I know ATC has limited Freqs, but having another flight attempt to contact a wayward NORDO plane is not a new idea.
yes, these guys screwed up. but...oh well...better to start looking for a new job