The straight up fact is that a 2nd year fellow (who had graduated from a reasonably well-known academic IM program elsewhere with the scores and LORs commensurate to matching at Penn obviously) resigned less than six months prior to graduation after being called to meetings with the program leadership. To the best of my knowledge, there were no legal accusations of misconduct (malpractice, HIPAA violation, outside hospital legal violation such as misdemeanor, et cetera) against the fellow and there were no major health/family issues that necessitated the fellow leaving.
I'm sure both sides have different perspectives on what happened - which is why I posted. When I applied for fellowships, I wanted to see where all the previous grads of my programs had gone/done and if there were any that had left or been asked to leave, I asked the programs about it and (if it were a program I was really interested in), tried to contact the former fellow to see what had happened. I think this would be even more particularly true if I were applying to a field like nephrology and if I were the caliber of applicant like the former fellow who had received interview invites to multiple 'Name Brand' institutions. So this is just an FYI for anyone applying to Penn for nephrology as something else to ask about and see how forthcoming the program is; see if they'll put you in contact with the former fellow. If someone's the kind of applicant getting interviews at Penn, he or she may want to rank some other Ivy League place higher that doesn't have near-graduation fellows not graduating.