Dennis Allen's defensive scheme is clearly DL and DB centric. Here are the 2020 LB snap counts:

Player	Pos	Off Num	Pct	Def Num	Pct	ST Num	Pct
Demario Davis	LB	0	0%	1032	98.66%	6	1.32%	Demario Davis 2020 game-by-game snap counts
Kwon Alexander	LB	0	0%	350	33.46%	4	.88%	Kwon Alexander 2020 game-by-game snap counts
Alex Anzalone	LB	0	0%	525	50.19%	180	39.56%	Alex Anzalone 2020 game-by-game snap counts
Zack Baun	LB	0	0%	82	7.84%	247	54.29%	Zack Baun 2020 game-by-game snap counts
Craig Robertson	LB	0	0%	23	2.20%	360	79.12%	Craig Robertson 2020 game-by-game snap counts
Kaden Elliss	LB	0	0%	5	.48%	276	60.66%	Kaden Elliss 2020 game-by-game snap counts
Chase Hansen	LB	0	0%	1	.10%	24	5.27%	Chase Hansen 2020 game-by-game snap counts
Andrew Dowell	LB	0	0%	0	0%	11	2.42%	Andrew Dowell 2020 game-by-game snap counts

Davis was in on 98.66% of defensive snap counts. All of the other LB's combined weren't in on that many. That means they averaged less than two LB's on the field for the season on defensive snaps.

The defense clearly isn't designed for the LB to be that impactful. That isn't because of any draft success or lack thereof. It is based upon scheme.