They went to back to back finals with 3rd lines that were used predominately in a shut down role.
First of all, mostly everybody scored poorly compared to their career norms under Knoblauch and, secondly, the main reason why the Oilers fell off hard last year was because their defending was quite a bit worse. Depth scoring is a need but the defensive regression from their forwards and defense was also a big problem. The problem in the Anaheim series was predominantly McDavid being a massive liability, not their depth players, and the PK but I think that was also a coaching problem.
Dickinson had scored 30+ points two straight years before the last two and he showed off some goal scoring skill in the playoffs last year so I don't think it's impossible to expect some offense from him going forward in addition to being solid defensively and on the PK.