You cant one day be perfectly healthy and the next day loose it,
I'm still inclined to feel you're right. Usually there are clues well before a major BP departure from the norm.
My experience: I have posted on JB, I have, or had, three friends who were seriously Bp. All of them are dead. One murdered at 22years old, one suicide and one -? After a lifetime of just having a mix of friends, this cluster happened within c 5 years. Very puzzling and very distressing.
While thinking about this today, I recalled a captain, a senior man who was a pall of the owner, just started doing odd things. Our shiny new jets were not quite up to his standard inasmuch as the cockpits were not clean. I recall vividly him licking his finger and rubbing at the dirt and proclaiming, "see, duck egg blue. That's how it should look." He re-licked the filthy finger and repeated the process - several times. He then went on to suggesting brushes be issued to the engineers so that the dust between the radios could be swept out of the groves. I heard later he'd been delaying flights while dust was removed and the duck egg blue restored.
I imagine the next game of golf with the boss was a little strained.
I've wrestled the controls from my captain in the Innsbruck valley, and years later, stormed out of a very good job because of the bizarre and very, very dangerous practices of a captain in a well-known independent. I'd had enough, and no one would listen. So many respected captains knew, but no one did anything.
It had gone on for over a year.
The thing is, in this case, were there any clues prior to that day? And if there were, was there anyone that had the skills, and indeed the balls to take action? People I had admired were manifestly unable, or unwilling, to make these difficult decisions, so are modern management any better?
I'm sure they will be now. Cow. Gate. etc.