I can see this happening occasionally but would be surprised if a club kept mistakenly leaving one of their better players on the bench. Must have been a reason. They track players pretty closely.
I was watching a lot of their games and I do recall in a number of them that players were just getting stuck on the bench. Happened with Dunkley a few times too. Could have just been bad luck with the flow of play and scoring not allowing them to get the rotations they wanted? Perhaps it was just a symptom of their overloaded midfield with some new kids coming in to play roles?
This talk about him having fitness issues doesn't make sense to me personally because A) he is 28 and should still be at the peak of his powers football-wise and B) I don't recall not seeing him run out a game like he usually does last year when he was on the field and there were several where he did rescue his score with a late flurry of possessions.
Maybe others see something I don't, but I can't reconcile these sudden concerns that he's over the hill at 28 based on what I recall from last season.