From what I've seen and read, all DL in the 3-4 are basically tackle types meaning that bulk, size, and strength are really more important than pure
athleticism (of course you'd prefer players with all qualities). The DL contain,
nuetralize the OL and the backers are free to tackle the ball carrier and pass rush - the OLB are where you're best athletes are. The 3-4 is cap friendly -
you don't need high profile, expensive DL (think Kearse & J.Taylor), and the
OLB can be played by tweeners who aren't really suited for DL or LB in the 4-3
(think Babin).