I've had the pleasure of working with a CR from Nesba who shall remain nameless. None the less we've been learning a lot about tires and suspension.
One thing for sure is the number of heat cycles regardless of the tread depth.
We found out the hard way, "the tire may look good but sticky went away".
This can happen on one side only or the whole tire. The number of miles don't mean anything compared to the number of times a tire has been heat cycled. Typically on the street, you will not get the tire hot enough to be concerned.
But the reduced pressures run on the track, with extra stress on the body, will definatively cycle the rubber compound.
Do you run warmers? As I recall, you do not. This means as you go faster at reduced pressures, you will be cycling the tire every session. After so many cycles, the rubber looses its tackiness or stick. We've got a stack of take offs that are all good on the street but one side has lost that tackie feeling at temperature. My son's multiple lowsides are a result of one side going away.
We've dialed the suspension for specific tracks only to find one side going away before the tread shows any indication of a problem. Every manufacturer and compound will react different for every track relative to the conditions. The real goal is to learn how to read the transition from traction to no traction.
Two keys to reading the traction are the rider feedback and feeling the tire surface right after a session. Rider feedback may be, " ya, it seems like the tires are squashing or feel like rocks". The surface on one side will glue your butt to the wall but the other side is like fresh grease.
Pressures are parimount with appropiate suspension settings to equalize those effects. Yet the temperature and humidity of the day can cause change as well.
All this aside when you put an expert rider on a bike. The riders skill to adapt to such varying set of conditions is truely the miracle of speed.
If there is a way to formulate the ideal condition, and I find it, I'll share with you all. For now, I can say with all confidence, stay with one variable at a time and learn to adapt as the weather changes with your riding techniques.
Sorry to be so long winded.
This is a very complex subject.
As far as your crash is concerned, don't look for a single cause, it will drive you nuts. Like me.