This hits the nail pretty firmly on the head. You need to base judgements on managers on they're performance alone, absolutely nothing else. To use what has happened in the past to form opinions on whether to sack managers is an amateur way to run a football club, because if they do as I predict and don't sack him because we've sacked too many managers in the past then what will happen is they will be taking those (right or wrong) decisions to sack previous managers to invariably force them into making a wrong decision in not sacking him without realising. To use an analogy, mobile phones works pretty well where the phone is the manager and the owner is the board.
Wilson - You choose a decent phone and it's performing pretty well. For some reason you decide to replace it. This is not the fault of the phone but the fault of the phone owner for replacing a phone that didn't need replacing.
Weir - You choose a cheap phone that hasn't really been proven to work before. It transpires to be extremely faulty so you get it replaced. This is the fault of the phone for being faulty but more so the fault of the phone owner for choosing a phone they knew might be faulty.
Clough - You choose another phone, a big improvement on the previous phone but in the following year starts to really underperform, so you get it replaced. This is the fault of the phone for being faulty but more so the fault of the phone owner for choosing the wrong phone.
Napkins - You're fed up choosing shit phones from the previous 2 so you go all out and blow it all for the latest new iPhone. Very surprisingly and against the odds, it starts performing remarkably badly, even worse than the previous one. This is purely the fault of the phone for being shit and not the fault of the phone owner.
Now, you don't just not replace it and put up with a terrible phone because you've been a shit phone owner in the past and chosen phones that don't work. Even though you did everything you could this time to choose a phone that would work by going for the most expensive, you accept you have been unlucky for once in choosing yet another faulty one and get it replaced.