One thing that really intrigues me about Jeff Caldwell: according to Rob Rang (I think), Caldwell was 5'8" as a high school senior. He grew 9" in a late growth spurt. This might explain his lack of production prior to Cincinnati. That's a whole new body to learn how to use.
Another intriguing thing: Caldwell not only ran a 4.31 40 with a 40: VJ and 11'2" BJ. He had a 1.53 10-split. That kind of quickness is almost unheard of for a 6'5" guy. (Full disclisure: Chris Brazzell had a 1.52 20-split).
He may never reach his potential, but the potential is other-wordly.