One of the benefits of running Spaz's Cover 2 defense so long was that every player knew what to do, especially by the time he had been in the system a year or two. Smart players then almost become coaches on the field because they could then help put other guys in the right spot. (The real breakdown of Spaz's D occurred as the talent declined and McGovern and Spaz couldn't get on the same page once Spaz became head coach.
When Don Brown took over the D, he implemented his heavy blitz package. The was about as opposite as could be from Spaz and took a few seasons to adjust. We didn't have the talent or experience. But once he got both, the D was lethal. He put a lot of responsibility on his DBs, but they delivered and BC had one of the best Ds in the country. Once Brown left, BC then saw things erode again. It was partially due to tweaks made by his successors and a drop in talent.
This brings us to the Jeff Hafley/Tem Lukabu. A first time Head Coach and his first time Defensive Coordinator. They worked together at Rutgers, but I don't think they will be running Schiano's old scheme. We know from Ohio State that when Hafley had his own D, he ran a Cover 3 in the Pete Carroll Single-high mold.
The Cover 3 in Carroll's world puts the DBs in single coverage where they are trying to prevent the big play and funnel the WRs into certain areas. They play behind the WR so it might appear a little soft and won't manhandle the WRs like the Don Brown DBs did.
With the DBs preventing the big plays, the LBs (and a Safety) get all the underneath stuff. This helps BC since our LBs are probably our most talented position group on the defensive side.
At Ohio State, Hafley also had all defensive players watching the ball. There weren't run stoppers assigned...they were all supposed to stop the run. Help, leverage and keeping assignments simple were the key. The front guys are reading the backfield and chasing the QB and/or RB.
If Hafley follows his Ohio State model, his D will be pretty simple and standard. Not a lot of blitzing or anything particularly unique on early downs. It will seem more like Spaz than Brown.
I think simplifying the D will make things better than they were last year. Clearly there were lots of assignment breakdowns. That alone will make a difference. Hafley also put an emphasis on tackling at Ohio State. I hope that improves as well. But we will all find out more on Saturday.
For more reading on Xs and Os under Hafley at Ohio State, I recommend these three articles: