Your DE, DT, and other DE are not impressive. Your LB core though, very, very, on point. Top 5 in the league honestly.
The redskins starting d line had 14.5 sacks last year, which is superb considering their main job is to keep the stars of this system (the LBs) clean and they did a great job at that considering LOndon Fletcher led the league in tackles last year. Cofield also batted 8 balls at the LOS leading defensive linemen. Yes our LBs are good (like you say probably top 5) but Part of the treason they are so good is because our d line does a great job of keep them clean
Then you think about the fact that Cofield pretty much learned 3-4 NT on the go last year as he didn't have a training camp to learn the position after spending the first four years of his career in the giants 4-3. It is also this d lines second year together. They are all 28, this group can only grow