A. Nelson is arguably the best pass rusher in the conference (if you don't believe me, PFF had high ratings for him all season and the vaunted Nick Bosa only had 1 more sack). Hesse is going to be a 4 year starter with tons of experience. No DE on the team sets the edge better than he does, and it shows. M. Nelson was playing very well by the end of the year, and Lattimore has shown flashes. Epenesa probably needs no explanation due to his natural talent and the fact that this board drools all over him, and Sam Brincks has proven to be a solid depth player (to the suprise of many). Add in Nixon who is sure to play right away, and that's a pretty salty defensive front.
Maybe great was a bit of an overstatement, but they're pretty damn good for sure.