Defensively, I think ALL our problems are with the front four. They don't pressure the passer and they don't keep our linebackers clean. Although it's not reality, I would love to see what our linebackers would do if Suh was there drawing double-team blocks every play. Godsheaux is OK; probably better as a reserve. Hood and Wake's best days are well behind them. Harris? Bust. But, I mean, our starting DTs would be backups on most teams and our backups wouldn't be on most rosters. We didn't adequately address that position with the loss of Suh, and it's shown all year.
Our LBs aren't perfect. But, IMO, they are good enough to play for a team that could win in the playoffs. Alonso does make some bonehead plays from time to time, but, for the most part, he's played well. McMillan and Baker are in their first year and I think both have gotten better. But when they have linemen getting to the second level and they have to deal with them, they are neutralized.
I think our secondary will be very good next year, providing they don't have to cover for eternity on every single play because we have no pass rush.