[Sheriff Gonna Getcha]

First, I doubt we'd get anything higher than the 25th through 45th pick. Everyone knows Coles wants to leave and we may release him. Everyone also knows about Coles' toe. So, forget about getting a high first round pick for Coles.

Second, I do think we need some new blood on defense. With Smoot's likely departure, we either need a new corner or a pass-rushing threat on the defensive line. While I like Walt Harris, he's not as good as Smoot and he's getting long in the tooth.
If we lose some of our ability to cover, you need to make it up with some pass-rushing threat. While Griffin played great last season, he alone doesn't bring consistent pressure on the quarterback. Salave'a and Wynn are good run stuffers, but they don't provide a pass rush. Warner, Evans, and Daniels don't get consistent pressure either.

While Williams is good at masking weaknesses on defense, he can't hide what is apparent to everyone - we don't have a pass rush without blitzing linebackers or defensive backs. Regardless of how good our linebackers and DBs are, you bring some heat with them and you also open up holes.