Because that’s the job of a manager. He doesn’t go out and play the football, he gets results through the players. I appreciate you have only mentioned this game, but he has been forced today to make those team changes for instance, and he is too slow to react - his team selections should have been different as far back as the first game at home to Fulham.
We cant on the one hand say he kept us up last season (appreciate you may not have said that) and then on the other absolve him from results. Once you start picking and choosing which results are on him or not on him, it becomes messy. His job is to get results in each and every match and win, lose or draw, he is accountable. My view is simplistic, it is on him for every game (not absolving KT/BK or FM by the way) but to start the season with three losses, six conceded and no goals scored is somehow even worse than last year.