my guess at the defensive draft philosophy:
Gannon being a DB coach by trade, I think the defensive philosophy is to get a deep group of DBs who can cover and force the QB to go through progressions / and run a scheme that limits big plays.
This means a rotational group of C+ to B front-5 players can get enough pressure over enough 3rd downs to limit offensive points.
This doesnt mean they dont want A+ level front 5 players, but it means its not a requirement for an adequate defense.
It also explains why in Monti's first two drafts, they have taken 6 DBs to 4 front 5 players -- even though Monti started with 2 vet DBs but nearly 0 starter level front 5 players.