re: Dave Aranda has to be fired today or after next week, right?

Agreed. Also keep in mind the game has swung towards offenses, especially in the last 5-10 years. Nobody has a shut down defense anymore, those days are over.
But dialing up a successful blitz, or getting an occasional sack or turnover or somehow back into a 3rd down stop , would be enough to win big with the offense we have this year.