Its a fair point on confirmation bias - we can all be guilty of that.
Id agree with him personally the attitude has been off - personally i read it as over confidence if anything - the players think they will be more then all right without deductions (presumably) this year - is a way i think they think this year will be easier - we've been guilty of that ourselves this year.
Overall the standard has dropped and these players aren't good enough for standards to drop, im thinking of who has become disillusionment, not Pickford, JT and McNeill have played for him all their careers so not them - pretty much everyone else is lucky to have a PL career if he wasn't here as a manager and we had sever limits - so they would be unwise not to be giving their all. There are a few with a foot out the door as well in the last year of their deals and Dom of course with a fot out the door.
These have always been a group of players who given an inch can crumble or attitude can disimprove.
Id say the former is all more likely rather then players downing tools or disillusionment if we are calling it that.