To bring it back to the comparison of Freeman vs Lea defenses - this year's defense has given up 22 points per game and scored 2 touchdowns (so essentially a net of 19.66 ppg). ND's offense shouldn't get credit for the defense's two touchdowns and ND's defense shouldn't get dinged for the 2 pick sixes from Coan and Buchner.
Then you've got 6 ND turnovers that led to 30 points for the other team where the opponent is starting out on average at ND's 41 yard line - almost in FG position.
And then apart from the defensive TDs, ND has also scored 45 points off turnovers created by ND's defense that gave the offense an average starting position of the opponents 39 yard line.
So while ND's defense was better last year, I don't think a ppg comparison really captures the whole picture. Through 6 games last year ND's O had only turned the ball over 4 times and the defense had forced half the turnovers as this year's defense with zero defensive TDs.
Football Outsiders has a
defensive FEI rank that basically sums up all this data (field position, turnovers, yards per play, opponent quality, etc) into a ranking. ND is 16th this year. ND finished 24th last year (almost certainly would have been top 5-10ish through 6 games last year before the 2 Clemson games and Bama). The biggest weakness this year for ND is yards per play - which is a direct result of big plays caused by poor tackling. Almost every big play we've had guys in position and just missed. Definite cause for concern, but if we can clean this up then we could be looking at an elite defense. It's also worth wondering how the defense does if it has Liufau, Moala, Simon, Hinish vs. Wiscy/Cincy, or Bothelo on the depth chart as well.
When BK talks about needing a defense that sets up the offense and creates big plays, this is what he's talking about. To me the offense is almost entirely the problem this year. To be completely candid, I think it's worth wondering if the team is 5-1 this year with last year's defense. I don't think last year's defense is changing the outcome of the 10 points Cincy scored when given the ball at the 8 and the 17 respectively. And I don't think last year's defense scores 2 TDs and sets up the offense for 17 more points with short fields against Wisconsin. I do think the FSU, Toledo, and VT games would not have been as close though. So it's a give and take.
The one area I would like to see Freeman improve on is in game adjustments, as many have noted here. I loved the way Lea's defenses were able to really lock it down in the second half and adjust to take away what was working for the other team. We haven't shown as much of that ability so far this year.
But overall I don't think the outlook should be anything but cautiously optimistic for this defense.