I'll just go ahead and spill it. Hankins was a first rounder based on talent and highlight tapes. When you turn his game-film on, you still see a dominant player, but you also see a guy who can't go multiple series without faking an injury.
I stated before in the Hankins thread that his stock would likely slide, well before final mock drafts or official prognostications, because of the fact that he faked injuries so frequently to get off the field.
Personally, and this comes with some insight as well, the NFL cared less about his conditioning (that can be worked on), but way more to do with the attitude it takes to stop a game multiple times during a season with a fake injury to get off the field.