I agree that better coaching wil show, and the D will improve. But, I think some people are in for a little disappointment when teams continue to score fairly easily on us. Let's be honest, 70's ranked defense, while improved, isn't going to be shutting anyone down
Personnel wise, we are better suited to run the 4-2-5 than we were the 3-4.
We had several decent (thinnish) defensive ends that were okay at the pass rush from the outside, but they were too small to operate in the traditional 3-4 scheme. Childs comes to mind. Felder (if healthy) could probably be another. You also don't have to ask the underperforming DT's to be as disruptive as you did in the 3-4. We can now get away with 240-250 lb. ends and 280 lb. tackles. We couldn't do that before.
Also, we have a bunch of 'tweener' linebackers that probably will fill the "Cat", "Stinger", or whatever you want to call the S/LB hybrid. Tigner is one. We recruited a bunch of smallish LB's to fit the cover 2 scheme when Morris was here, and they had no business being 3-4 linebackers. They may actually have a place here now.
I feel okay about the safeties if they can stay healthy. Herndon will be a decent strong safety, and if Hartman actually learns something, he may develop into a decent free (he is probably a tad slow though). If we can keep Moore out of trouble and qualified, he'll provide the lockdown corner we need. However, after that, pray the front seven gets to the QB before he has a chance to throw because our collection of corners is about as bad as it's been since the early 90's.
I'm in agreement with most that we can see a significant jump in defensive rankings, but if this defense gets below 60th in the nation in total defense and scoring defense (with road games to OU and Tech on the slate), Koenning should win the freaking Broyles award.