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Notre Dame’s defense has limited scoring, but what keys have led to that?

In looking at some preseason predictions, this space speculated Notre Dame would give up between 23.6 and 25.1 points per game this season. That would have been in-line with last season’s final seven games, a period in which the Irish defense performed much better than may be realized, allowing only 23.9 points per game. Such a mark would demand respect and set up Notre Dame for success. After all, if the offense could muster three touchdowns and a field goal, the Irish would claim victory more often than not.

That average currently stands at 16.5 points. Let’s put that in starker terms. If Notre Dame gave up 33.7 points per game in the season’s second half, the 2017 average would still rise to only the upper-level of that preseason window, 25.1 points per game.

Clearly, the Irish defense has been good. Defensive coordinator Mike Elko has proven deserving of every inch of offseason hype. Frankly, more probably should have been offered.

Just like Wednesday with the offense, let’s turn to a few key previously-discussed statistics to read into the defense’s success.

RELATED READING: Four key statistical tidbits and a $4 cost (Sept. 1)

A statistical look at Notre Dame’s offense through six games compared to the past

Third down conversion percentage allowed
2017: 34.95 percent
2016: 38.95 percent
2013-15: 39.34 percent
2012: 36.52 percent

Anytime a defensive metric surpasses 2012’s standard of excellence, it should be noted. Admittedly, the Irish have yet to face the stiffest challenges this season. That onslaught will begin with USC next week. Nonetheless, six games is not a negligible sample size when discussing college football. Whether that 2017 rate remains below the mark set by the peak defense of Notre Dame coach Brian Kelly’s tenure or not, it is a pace indicating sustainable success.

For that matter, the Irish defense ranks No. 50 in the country in this category. More of note, though, is no team ahead of Notre Dame has opposed more third downs (103). This speaks to two things. First of all, Irish offensive coordinator Chip Long does keep a quick pace, somewhat aided by the big plays the running game has provided. Secondly, Notre Dame’s defense has not made a habit of giving up big chunks of yardage on first and second downs. The more third downs forced, the less likely an opponent is to string together enough to sustain a damaging drive.

Average yards per pass against:
2017: 5.85 yards
2016: 7.53 yards
2013-15: 6.84 yards
2012: 5.98 yards

In other words, the Irish have not given up many big plays this season, especially through the air. No matter the opposition, a single mental lapse can balloon this statistic at any point. Avoiding that is a clear sign of defensive focus and, pardon the simplicity of this thought, competence.

(Photo by Joe Robbins/Getty Images)

Rush attempts against per game:
2017: 34.0
2016: 42.92
2013-15: 37.73
2012: 27.85

Some will argue this statistic is skewed by Notre Dame claiming all five of its victories in decisive fashion. Perhaps it is diminished slightly by that fact. More than that, however, this points to the Irish defense minding assignments and limiting consistent rushing yards, thus greatly discouraging opponents from relying on the ground game. Even if big plays are not likely to come in the passing game, at least some yardage can be gained.

It should be noted here: This speaks to Elko’s work with the Notre Dame defensive line. Such an improvement never would have been expected coming into the season, and this change set the foundation for any further defensive success.

Turnover margin:
2017: plus seven in six games, or +1.17 per game.
2016: negative four in 12 games, or -0.33 per game.
2013-15: negative nine in 39 games, or -0.23 per game.
2012: plus eight in 13 games, or +0.62 per game.

This was mentioned Wednesday. This will be mentioned again Friday. This point cannot be mentioned enough times.

It is much easier to win games when your opponents’ possessions turn into your scoring opportunities. Forcing 14 turnovers to date, the Irish defense has done that more than at any point in this window. Even that vaunted 2012 defense managed “only” 23 takeaways. (And let’s remember, five of those 16 interceptions came on five consecutive Michigan pass attempts in truly one of the most absurd play-by-play sequences in gridiron history.) (And to anyone reading that previous parenthetical sentence but not remembering that Sept. 22, 2012, contest — it is not an exaggeration. Literally, five Wolverine pass attempts in a row were intercepted.)

To summarize: Notre Dame’s points per game will rise in the second half of the season. The yards per pass against likely will, as well. As long as the Irish continue to limit third down conversions while driving opponents away from the running game, the defense will still stand out as an unexpected success. Every turnover will only enhance that strength.

Got questions? It’s bye week. Let’s try to answer them.
Later this week, this space intends to run a mailbag. If you have any questions for it, drop them into the comments below. They do not need to be litigated there — and they just might “disappear” if they are — but good ones will be noted and hopefully answered by week’s end.