Statistically, we're much better, though we haven't faced Clemson or UGA yet.
I'm more impressed with how rarely we seem clueless and out of position, and how much better the tackling has been. Last year we could barely even get the defense set if a team went into any kind of hurry-up, and Middle Tennessee State seemed to run wide receiver screens every other play and we had no clue how to stop it. There were also plenty of times last year when guys would shrug off 3-4 arm/shoulder tackles to score touchdowns against us. That hasn't been the case this year. There have been several instances this year when our guys looked like they were out for blood, against UVA especially.
But again, we haven't faced Clemson or UGA yet. I think Roof will do good things here. I just hope there's not a butthurt tsunami if the defensive output against these teams looks closer to the Miami game than the games against Pitt, Duke, Syracuse, etc.