We don't have the pieces for any kind of decent defense now so all of it has to be rebuilt anyway. The only DEs we have under contract are Foskey and Granderson. Maybe Kpassignol too but I'm not sure. So we have to rebuild anyway and the defenses that have been stopping modern NFL offenses are 3-4 or 3-4 hybrids that use B gap pressure with a 2 high shell over the top. Plus LBs are cheap and easy to acquire and are usually great value in the draft.
Plus Breese and Cam work as 3-4 DEs and the idea is to be multiple not just run a 3-4.
It has nothing to do with the Dome Patrol days.