Yes, he’s failed twice. He’s been fired and not renewed from two jobs with significantly better rosters than what the Saints are working with right now.
If you are an accountant and get fired after 5 years, you don’t get to be like, “well 4 years ago I had a pretty decent year!”. You were bad enough that they didn’t want you anymore - that is failing the job.
Also, 1 Super Bowl with Rodgers and that cast is not a flex, it’d be humiliating if prime Rodgers (maybe the most talented QB ever) didn’t get you 1, especially when you consider the skill players and defensive talent he inherited in GB. Just like he inherited a great roster from Jason Garrett, who was massively underperforming.
Now you want him to inherit the worst roster he’s ever inherited, after he’s slowly but surely plummeted every team he has coached - but no, he’s going to come to NO and magically overcome all of that.
Be realistic.