This. Times 1000.
I don't think some on here understand how BAD our LB unit is. I think most of us agree our secondary is good. Well if you take how good that unit is and inverse it I think the LBs are actually worse than that. If you key on them they routinely fill holes by blindly crashing into holes and or blockers. They don't use their hands or keep their head up, which often leaves them susceptible to losing contain or being unable to shed blocks. All of them are pretty horrendous in coverage and none of them are particularly adept at making tackles in space. You can cite youth, you can cite inexperience, but it's kind of scary we are in a position to have play freshman LBs who aren't studs. Instead we are playing them because LB is (by far) the weakest group on the team.
Thus far Heacock has been reluctant to do some of the things he said he wanted to do preseason. Personally I think we should be more aggressive, lean on the secondary more, and utilize more 4 person (lineman) fronts as their isn't much reason to have 3 LBs on the field when it's a weak position group. I think he can alter is fundamental base without necessarily (entirely) changing the fundamentals of his defense.
Luckily the only elite 3rd down offense we've played was OU and, to no surprise, they destroyed us. KU and KSU will be two of the better 3rd down offenses we will play. When we've lost TOs, 3rd downs, and to a lesser extent penalties have often been fatal. Against OU the combination of the TOs (pick 6), blocked punt (safety and ensuing FG), and 3rd/4th down conversions (essentially OU was 9/14 in converting third downs as they were 3/3 on 4th) did us in defensively. I think the latter will loom extremely large considering the offenses we will play. I'm leery the LB group will be isolated/picked on as much as possible.
Finding LBs will be vital in the portal this offseason. It's a terrible group.