I agree we have issues with players and the board but it shouldn't deflect the fact that the manager is doing a rubbish job. We either have manager who leads us to success early before going rogue or have a manager who is just crap.
You said the board prefer the players over elite coaches, which I agree on the basis that they give dumb contract extensions, but let's not forget that the manager can make a statement with those you mentioned by not picking them but they do not. Mourinho/Conte, for example, kept picking Willian and made him integral to their teams. Sarri kept picking Alonso, at least until recently, and made him feel important to the team (even said he's one of the best LBs in the world!). So rather than just blaming the board, you should also question why the manager keep on making these poor quality players important in his team.