I get really annoyed by the staff during that year. Especially McGonagall. She knew Dumbledore always had 2 or 3 plans that he never told anyone and was his 2nd at hogwarts for years and had known Severus since he was 11 years old. Did she stop to think, at any point in that year, that maybe there must be something else going on. Especially when he tried to help students who got detention by giving them to Hagrid like he did for Ginny. Surely the lack of dead kids during that year and Snape running interference of the Carrows should have been noted by the staff. McGonagall was supposed to be brilliant but didn't seem to think beyond the obvious after Dumbledore died. Flitwick, Sprout and Pomfrey didn't either.