TCF, to me, his injury history scares me away. Of course, when he has been in the hands of multiple teams and their medical staff, most likely things are going to leak out, and that will give us fans a better idea of what will happen to him. Because I agree that his performance the last two seasons alone should warrant at least a top 15-20 pick.
As it stands right now, I think he is a guy that you strongly have to consider taking a shot on at #27. If you hit jackpot, then you have a pass rush monster for many years.