There are obviously roster and contract-issues with the Oilers (duh!) going back to the Chiarelli-legacy effect, but in my opinion---and, of course, this is only speculation as a distant observer (really distant, in my case)---the core problems with the Oilers are not coaching, or goaltending (horrible as it's been this season), or even defence-core (relatively poor as it is).
In my opinion, there are 2 fundamental problems with the Oilers, and it's largely been the same 2 fundamental problems since autumn 2017:
1) Leadership / Personality issues with the core players
2) Lack of bottom-six forward support
To point (1), I think it's now clear that the collective of Nurse, Drai, Nuge, and McDavid do not have the winning mentality of Messier, Gretzky, Lowe, Kurri, etc. We're in a very different era when young players are mollycoddled more and are protected more from the media and public by the team, which has its good points, but which also means we may arbitrarily end up with a "leadership" group with all the leadership capacity and charisma of the members of a high-school chess club. Nurse has an incredible inability to learn from his own mistakes and improve his game---he literally has learned nothing since the Anaheim gave 5 choke in 2017. Nuge is melted-butter soft and doesn't show up in the first half of seasons. McDavid has shown great mental fortitude at times, but he often gets visibly frustrated and has the personality of a wet noodle on camera, which makes me guess he has a similarly vacant personality in the room. And Draisaitl cannot control himself when he gets frustrated, specializing in stupid penalties at key times. Look at the last game -- the score was 4-2 with eighteen minutes left. It's still a winnable game if everyone stays focused. Instead, Drai and McDavid (like Crosby's meltdown in 2012, but he learned from it) start taking penalties and misconducts, just throwing in the towel early.
And what can be said about point (2) that isn't obvious? The reason the Oilers exceeded expectations in 2016-17 was that they had an actual bottom-six that supported the top guys. As noted, there currently is 1 secondary assist and 1 empty-net-goal assist from the bottom six on the season. This isn't rocket science. It doesn't matter if you have 150-point guys up front, or if you have 85-point guys up front. Neither situation is winning anything unless you have support across the four lines in the line-up.
Unless the Oilers quickly address these 2 fundamental issues, I can't see them going anywhere. They can fire Woodcroft (whom I basically like, btw) and hire the 57th coach in Nuge's tenure (what's the definition of insanity again?), and they can trade for a mid-level goaltender, or they can acquire a bottom-4 defenceman, etc. It's all nice, but none of those things is going to address either of the two fundamental problems.