The secondary was a weak spot in 2015, and it was made even weaker by the retirement of Charles Woodson. To address that, Oakland added a big, tall cornerback (Sean Smith), a seasoned safety with ball skills (Reggie Nelson) and an instant-impact rookie (Karl Joseph). But the Raiders didn't stop at fixing deficiencies -- they also boosted a strength, further augmenting their Khalil Mack-led pass rush with veteran Bruce Irvin and draftees Jihad Ward (who has lots of upside) and Shilique Calhoun. The latter player is a real sleeper who played very well at Michigan State as a down lineman and should find a spot as an outside linebacker. Defensive line coach Jethro Franklin is a hidden gem, in my opinion. He's really good at what he does and is extremely knowledgeable, as I can personally attest after sitting with him at the NFL Scouting Combine.