Have studied the 3-4 scheme a bit. The thing is, if you want to be successful in the 3-4, you MUST have a space eating NT and two DE's who are basically athletic DTs. NT plays at +330 lbs, DEs in the 300lb range. The principle of needing to be strong up front still applies - it's like the core strength of your body: if you aren't strong in your core, all of your important power and olympic lifts like squat, snatch, overhead press, clean, etc will suffer. The same is true in football - OL and DL strength or weakness can have a huge trickle down impact on the 2nd and 3rd levels. I don't care how good your backers are, if they are having the fight through the traffic, chip blocks, and garbage mucking up their reads and flows, they start to look very average in a hurry. Regardless of whether its three or four up front, if they can demand attention and force OLs to stay on those blocks longer, it frees the LBs to see what's in front of them and get to where they need to be to make plays. The big advantage of the 3-4 is that it frees you to cover an offense that forces you to cover sideline to sideline.
The 3-4 defense requires a very specific type of player at NT and OLB especially, and I don't think Nebraska had a single upperclassman who fit their needs last year.
I think there was a lot of excitement about Ferguson last year, as he came on strong at the end of the year but had trouble staying healthy. I think if he stays healthy, he probably has a really good year. I'm most excited about seeing how he has come along. I'm sure you've noticed this with Hawks players at LB, but the older they get the "faster" they seem to play, mainly due to repetitions in the film room and on the field allowing for them to react to what is happening in front of them rather than processing/thinking.
Honas is a bit of an unknown, IMO. He was swimming in it, mentally, last year, and the light bulb was just starting to flicker before he was injured. I guess, if there is a silver lining, he got about as much playing time as a guy can get and still was able to redshirt. But a lot of times it takes a player two years to get back to the point where they were able to move like they did prior to tearing a knee ligament. We will see.
Jojo Domann did some nice things at OLB last year. He started the year at safety. We could use about 7 guys like him - he is just a good football player and he loves contact. Iowa has a few guys like that - they just are good at playing the game, measureables be damned. He's a tweener right now. He's a little small to play OLB strictly vs Iowa and Wisconsin run games in the 3-4 (6'1" 225), but he's too big and probably not quick enough to play a true safety. But he probably is one of the best natural football players on the defense, so they'll find a way to use him on the weak side or off the edge and in coverage packages at OLB.
After those 4, you're looking at one senior who is below average (Alex Davis) Collin Miller, whom everyone is waiting on him to play more consistently, and then some freshmen who will probably fill the 2 deep (Joe Johnson, Jackson Hannah, Nick Henrich) The first 4 should be solid, really, but it gets dicey in a hurry after that.