Leafs and Sabres made similar mistakes--they tried to build around the wrong defenseman. The Sabres with Eichel in tow thought Rasmus Ristolainen was that guy, and the Leafs tried making a go with Morgan Rielly.
Sabres drafting has also been pretty awful. Like the Avs, they too appear to have been pretty piss poor outside the top ten, and even then had one monumental whiff (Nylander's bro).
As for the Sens, despite the rollercoaster ride that was Eugene Melnyk, Pierre Dorion has them in relatively good shape. IMO they're much closer to contention than Buffalo. I don't begrudge them the Giroux signing one bit, it's similar to the Alex Tuch acquisition in Buffalo IMO. Sometimes, when your franchise has been in the dark for a long time and isn't a go-to destination for talent, it's good to bring in someone who actually wants to play there.
Yeah I agree, Pegula is an absolutely horrid owner. I kinda feel bad for Sabres fans. They went from a criminal (Rigas) who literally used the franchise like a giant credit card until he bankrupted it, then Golisano, whose most notable contribution to the franchise was...the Buffaslug, to Pegula.
Buffalo had Eichel but then did almost literally everything else around him wrong. Part of the problem was that Murray clearly game planned for McDavid and then didn't know what to do with the consolation prize.