He means gutting the roster so thoroughly that it was impossible for any reasonable offseason or string of offseasons could add enough talent to get the team competitive any time soon again. It completely severed the Sabres from competitive NHL hockey for two full calendar years. The offseason after the tank they added 4 20+ goal scorers and a few other guys and a goalie, the vast majority of whom had plenty of team success elsewhere after leaving here, and it was still only enough to be an 81 point team (ie bottom 10 EASILY). There was no real path back to contention outside of obscene luck, because it is unreasonable to ever expect an offseason as good as 2015's was in terms of net talent added to an organization. I know hindsight will lead everyone to say that "well they should have done this or that instead and they would have been fine." Sorry, everyone here and everywhere else was over the moon in those days. And the results were never even close to competitive because the starting point was as far back behind the pack as it is possible to be. Putting yourself there on purpose is a major reason why we are still where we are today, even if competent management since could have eventually fixed it. It's hard to get that competent management when you build the reputation that began to take hold in those tank years.
Wwhatever intangible substance they lost by severing themselves from the NHL, they have never come close to recovering it. They are the ghost of a baseline NHL franchise, let alone the sterling franchise they once were.