The St. Louis Blues have been a model of consistency overall since they entered the league in 1967. For a long time, they had the longest active playoff streak in the NHL (1979-2006).
That does not mean they have not had some bad seasons. Interestingly enough, their inaugural season was not all that great.
The Blues only won 27 games and went 27-31-16. However, they caught fire in the playoffs and went all the way to the Stanley Cup Final, so it is hard to consider that a poor season.
There have been plenty of other clunkers along the way.