1) They were handed the keys to the franchise with not only being gifted tons of playing time right away without having earned it but also getting those huge contracts based mainly on draft pedigree and in Eberle's case, one big offensive season. They probably felt untouchable as the golden children and never had any fear of being benched for poor play or feeling motivated to play for a big contract.
2) They are being paid as top dogs and realistically, they are great complimentary players. Too much pressure to carry a team and not good enough to do so.
Hall is the closest thing to a star and he has tons of holes in his game.
I like Nuge and Eberle well enough and they are good players who can potentially be very good in due time, but they aren't franchise players. Yak is still struggling to even find his niche as a top 6 player.
3) Lack of support all throughout the lineup. They have been asked to carry the team and handed the keys to the franchise because there's nobody else capable of burdening the load if they aren't performing. Little veteran support to lean on and no lines capable of picking up the scoring slack if they are shut down, Perron was the closest thing they've had and now he's gone.
4) No puck transition ability from the blueline. A big reason why the Flames forwards are ahead of the Oilers forwards is because of Giordano, Brodie, Russell and Wideman all of whom are light years better than any Oiler defender at transitioning the puck to the forwards, even Petry. It's tough for skilled forwards to play at their best when they don't have the puck.
5) 4 coaches in 5 years for Hall and Eberle, 4 coaches in 4 years for RNH and 3 in 3 years for Yak.
That's a shatload of different personalities to deal with and a lot of different systems to constantly have to adjust to over such a short period of time. Continuity is vital for developing young players, otherwise you have the chaos that we see. Furthermore, outside of Renney who I think was a good coach for their early years, they have all been the wrong coaches. Probably Nelson too as I think the Oilers are at a point where they need a vet coach to take them to the next level.
6) It's a bad mix of players. This franchise will never succeed with a core of Hall, RNH, Eberle, Yak and throw Schultz in there. Too soft and not a diverse enough skillset. They are done against teams that lean on them physically and close up their space. It's a predictable outcome every single time against decent to good west teams that they will get neutralized, or at least the west teams that dont' play pond hockey.
I think 1 or 2 will have to be traded at some point.
It's mostly a failure from management for many reasons but a part of it is that they aren't great players and are being counted on to be great players. Not their fault really, it just so happens that the Oilers had the misfortune of drafting #1 in the wrong drafts and they had the misfortune of being managed by the OBC.
They are clearly not the biggest problem but they aren't a big solution either at least not for the roles that they have been given as franchise saviors.