You are right that somebody in the chain of command allowed standards to be glossed over or faked - and those people need to be identified and held accountable. No question.
But the Commanding Officer is responsible for his command, period.
He has to know his people, his ship’s systems, his mission. He has a host of staff members responsible to him to keep him on top of every potential problem - but he’s the one on the dot and he owns his men’s deaths.
If I had been in his shoes, his useless OOD with have been the Library Officer and nowhere near a position of responsibility.
One of the first and hardest thing to do as a CO is recognize dead wood and get rid of it - fast, before they get somebody killed.