Everytime you say "this is the worst loss of this franchise", you just know another, even worse loss, is coming. So this is temporarily the worst loss in the history of this franchise.
This is one of the worst sports collapses I've ever seen. You have to go to the NCAA tourney of recent years to see losses like this. It's like Bills/Oilers '92-level.
The only thing that makes it not so bad is that it was a meaningless loss in a meaningless game for a last place team.