See, I don't believe that. I can point to a thousand examples where teams that are playing poorly look unfit. However, that is usually down to a lack of confidence. Players dwell on the ball afraid to take risks. Players are afraid to commit to tackles. Players abdicate responsibility so if a team mate screws up they will take the pesters instead. Players lacking in confidence also tend to hide, and that reduces the options. Plus some players are carrying knocks but forced to play.
Teams that stink always look a yard slower, but that is almost always psychological.
I also think that there was an inevitable lull after the prior season's league success. Great teams struggle to be consistently good and have to continuously refresh personnel even when they succeed. As counterintuitive as it sounds, I think our ability to quickly retain pretty much the same squad as the prior season was actually detrimental. A few fresh faces in key positions might have kept some of the old guard on their toes.