I'm guessing it wasn't assembled correctly. It looks exactly like the one I found on my truck after someone installed the inner race for the outer bearing on the backside of the outer bearing race. The balls were being held in place by the outer thrust washer. It worked for a while that way, got loose, then ended up looking like that. It would be easy to assemble it wrong with the inner race behind the bearing, instead of being held in place by the outer washer. The inner race is the last thing to go on before the washer, and nut. My bearing cage was trashed like that one.
