Your big piece of evidence that O’Reilly was less invested last season was something that he stopped the season before.
Sure, O’Reilly had a down year, and maybe mindset colored it on the margins, but his performance fluctuations are pretty much perfectly connected to linemate quality, and playing a nonsensical role that has proven to crater team and player performance.
I'm not trying to overplay his comments, only that he should have known how they would be taken and become a distraction. You, OTOH, seem to be completely ignoring that he called himself out for not playing up to his own normal standards last season. It was indeed a thing, and he took responsibility for it.