Answering the question asked, my least favorite HC (not necessarily the worst, though he’s in contention — which is a good thing bc it contributed to Snyder selling) is Rivera.
I swear it’s not recency bias, I felt contempt for Rivera in a way I’ve rarely experienced towards a non-violent stranger. Made worse because he had this underserved reputation for being such a good guy while standing behind Snyder after he no longer had to. Weird performative obsession with the military which is always a red flag for a non-military guy. Coward at the podium, always passing the buck and making excuses year after year after year, while sounding actually unintelligent (which obviously isn’t the case, but his coach speak was so careless as to be insulting to the fans he and Snyder were consistently losing). The last couple years lamenting that he was running the whole operation and didn’t have the bandwidth, when that’s the only reason he ever agreed to work for Snyder in the first place and he eagerly jumped into it.
I feel for the guy because his cancer sucked the vitality right out of him. He was a shell of the man he started as, by the time he left us (a trend with Snyder hires but his health was obviously a factor). Really by the end of year 2. So I won’t trash him for his lack of energy, care, or effort. It wasn’t just that he was BAD at his job though. I’d seen that often enough before. I don’t let him off the hook for his failings in conduct while losing here, which are many and which I’ve scratched the surface of above.
He sucked, but plenty of coaches had sucked here before. Zorn sucked, but I didn’t disrespect him as a man and leader by the time he left here, he was just in over his head and doing his best. I did however feel that way about Rivera, and seeing him on TV speaking with any sort of authority on coaching in the league makes me ill. His fragile ego, absolutely hollow leadership ability, and late defense of Snyder while here is what I’ll always remember. Not a man who walks his talk.