May be that the Devils situation was not ideal either, new coach, some new players and opening in Europe, but luckily for them, they were playing a team that is younger, also with a new coach, and that is trying to learn a much more complex system with 40% more "new (or relatively new) players".
The Devils had two new forwards that had not played with their core.
They had 3 D, but that brings me to the second point, which is Keefe mostly runs a 1-3-1 trap system, where the D hang back and it is extremely simple to learn. and every player has played in that system at one point or another throughout their development if they were playing organized hockey in the last 20 years.
Ruffs system is complex, that is why I really didn't like the hire, but it is what it is. As I think this team (especially the D), really could have benefited from a simpler, more rigid system to help them learn how to D after the Granato fiasco. Ruffs system relies on skating and high hockey IQ, (especially for the D) - which ironically was sorta what Granato was asking of them. The Sabres D is young and it is hard for young players to work on improving their games when they are solely focused on "Where should I be" and "what are my teammates doing".
*Note* - please do not respond to my simplistic answer about the difference between Ruff's and Keefe's systems. To stay on topic and avoid a strawman debate I did not want to go into deep detail of the differences. If you want to have that conversation, feel free to PM me and I'd be glad to have a hockey system discussion with you there. Usually when you reply to one of my observations, it becomes 8 post deep back and forth about something unrelated taken out of context - let's try to avoid that here. We are already into strawman territory here, as my point is that "this team was always going to take a couple of months to gel". If you take issue with that statement, then please respond, anything else is offtopic and probably something we do not need to subject the rest of the board to have to read.