A good album is a be-all and end-all for the majority of musicians. It allows them to tell a story, express their creativity, and sharpen their artistic abilities, but sometimes it doesn’t quite work out like that and artists are left sticking their name on a sub-par, effortless record.
This is especially true in the world of metal, as many bands that enjoy the success of a hit album also find themselves lumbered with a great many stinkers along the way. It doesn't mean they can’t have the brief moments of brilliance, however, as the worst albums out there can be home to some surprisingly good songs, and have provided live staples used by artists for years following release.
These diamonds in the rough can sometimes be a saving grace and go on to be bigger than the lousy album from which the originated.
For bands with long and storied careers, this is to be expected, but you’d be surprised how often this happens to younger and fresher bands...