You can't demand consistency when the roster has massive roster flaws.
Right off the bat, which year in/year out 100+ point team has a sub .900 goaltending tandem?
These are the results the Oilers deserve, you want to be one of those teams that's always solid for the most part, then invest properly and be solid at all three positions (forward depth + defense + good goaltending). There is no magic formula to it otherwise.
And yes, this will be the Oilers reality every year as long as they want to run these kinds of poorly built rosters.