Yes, I understand Wadsworth, and many of these busts were only busts because of injury. Wadsworth's injury ended his career, Nkemdiche has played in like 4 games total now, and has in no way had a career ending or debilitating injury. For all we know he could play the last 8 games this year and be successful.
Look before preseason I too had basically written him off, but he looked very good albeit against 2nd stringers, I am not willing to call him a bust based on him playing less than 50 snaps so far this year.
Nkemdiche got in very few snaps his rookie year, and very few so far this year. Granted he has yet to produce, but it is obvious he does have the physical skills to succeed, it is all mental and technique with him - and that can be improved. From the interviews I have heard with him, I don't think he seems to be a headcase at all either, he seems motivated and intelligent. If he does have a problem perhaps it is toughness, and a desire to improve but I don't really know.
Perhaps you and I viewed him different from day 1, I always knew he was a project pick. Statistically he did not do much in college, but his athletic skill and the flashes he showed are why the cards were interested in him. I always assumed it would take him a while to meet his potential if it was ever going to happen, he just has not had enough playing time yet to know whether he will get better of not.