The Bengals seem to love snagging fallers in the fourth round of the NFL Draft; recent cases such Carl Lawson and Andrew Billings come to mind.
For Lawson, it was his injury history and the concerns that projected onto his pro game. Billings, on the other hand, fell because of his lack of pass rush potential as more of a run stuffer in a deep defensive tackle class.
While neither of these players have performed as well as some hoped, both have been easily worth the investment the Bengals made in them.