More pics of the compressor

Callins,

This looks like an impact failure rather than a lack of lubrication failure to me. There is no visiable evedence of high heat in the bearing area. The bearings seem to have impact failure. I would investigate lack of preload on cap bolts, overload on the pistons or excessive bearing clearance. Good luck with your investigation.

Excessive big end bearing clearances may result in impacting but impact occurring in all stages , not very convincing.
Regards
Akhtar