Was Austin the Problem with the Defense?

[J24]

I thought we played well against the Ravens, Colts, and Dolphins to start off the season. Then we played the Steelers, Cheifs, Bucs, and Saints without Vigil, Dennard, and on top of that Lawson was underutilized and then hurt during that stretch of games.
I think we added a new system which didn't mesh with our players early on and we had a major weekness in our LB core which was easily exploited once Vigil left the lineup.