If I remember correctly, Stevens utilized the two point-guard lineup a fair bit at butler, so this doesn't surprise me in the least. Exum would be great for such a lineup, as a) he wouldn't be required to run an offense if on the floor with Rondo, which is good for a teenager, b) he has the size to defend opposing 2s, which is one of the occasional drawbacks of such an offense. Also, Exum thinks of himself as a point guard. If you convince him he's just a second point guard, you can perhaps mollify him about being on the same team as Rondo, as he's been vocal about not wanting to be forced into the 2 if the team he's drafted to already has a pg.