I would think that you may be thinking about this "problem" too much?
I could be wrong but, I would think that the evidence of trying to spin might just be from when the bearing was failing, extra drag causing the outer race to be being pulled on.
I would also think that this bearing would be carrying the most load/torque as it is right next to the primary drive gear.
As for lubrication, when running, the primary compression should be forcing mixture through the bearing.
Only problem I could see is maybe after a long lay-up the bearing could drain down and be compromised at early start up, maybe? Even this is a long shot, as all of the engine internals could be at the same risk?
I would think that the cranks you have got were just at the end of their service life.
Racing puts a lot more stress through a whole bike, let alone just the engine.
Racing and race tracks are pretty extreme places for an engine/bike.