I thought this blog entry from Birkett was pretty interesting as Lions coach Jim Schwartz explains his defensive philosophy. Just scroll down past the Jay Cutler article to read it:
OT: Jim Schwartz Defense Explained.
Two things jump out at me here.
First, the statement that he doesn't prefer to have Will and Sam LB's, instead preferring versitility. This makes Curry a lot more of a sensible pick.
Second, his used of the 3-3-5 in "nickel" situations, which is pretty much like playing against the spread. I guess RR isn't totally off the wall on defense.