Metrics such as rush defense, pass efficiency defense, and of course, scoring defense and even the sometimes misleading crutch, total defense, paint a clearer picture regarding any defense's level of play over the long haul.
But the following comparison between Notre Dame's dominant front four in 2012 and the group today is nonetheless alarming:
Sacks through 5 Games in 2012: 14 total, 13.5 recorded by a member of the starting or reserve front four.
Sacks through 5 games in 2013: 4 total, three from the starting or reserve front four.
Last year, Stephon Tuitt, Prince Shembo, Louis Nix, Kapron Lewis-Moore, Sheldon Day, Ishaq Williams, Kona Schwenke, and Tony Springmann served as the deepest and most successful front in the last two decades at Notre Dame. Thirty-one of the team's 34 sacks came from an eight-player rotation of defensive linemen and Cat/DE hybrids Shembo and Williams.
Just three of the team's 2012 sacks came from the back seven, with Manti Te'o registering 1.5, his inside linebacker-mate Dan Fox another, and cornerback Keivarae Russell a half-sack (on a crucial CB blitz late vs. Purdue) to account for the remainder.
"I think if you're looking at how we have pass-rushed in the past, you're probably looking at a group of guys that has not been more than three- or four-man rush," said head coach Brian Kelly. "We're not a group that sends five and six consistently. We generally play coverage.
"When we've needed to add pressure, we've done a pretty good job, and then this past weekend (vs. Oklahoma) we bring five and we give up a lane and the quarterback is able to convert.
"I think it's been a mixed bag. At times it's been better over the last couple weeks, but it needs to continue to get better, no question."
Formerly Fearsome FoursomeA consensus pre-season All-American, Tuitt has half of the 2013 team's quartet of QB takedowns through five games, with Williams and cornerback Bennett Jackson each adding one to the ledger.
Safety Austin Collinsworth added a quarterback hit in the end zone at Michigan that, had it not resulted in a diving touchdown interception by Tuitt, would have (or should have) instead gone down as a sack/safety due to intentional grounding. Consider that a more powerful fifth "sack" to add to the total, but yet another that came from an extra player blitzing to manufacture pressure.
Dominant in 2012, the front four has failed to inflict enough pocket damage to date.
"It's been decent. We can always get better," said senior nose guard Louis Nix of the defensive line's play this season. "I don't think I do the best job, especially when we don't win. I think I can do a lot better. We're just not getting there fast enough. There's been times we had a lot of hits on the quarterback, touched him a few times, been in his face, but I guess we're not getting to the ball fast enough."
Nix is correct that quarterback hurries are on par with last season, though the stat is so inconsistently tracked, it's barely worth noting. (For instance, the Purdue box score lists Notre Dame with no official QB Hurries -- my game notes show 13 snaps in which Notre Dame heavily pressured the passer.)
Why aren't the Irish getting to the opposing trigger man for loss this fall? Popular opinion offers teams are attacking a cushioned perimeter.
"I'm not in the film room with them, but it seems that way," said Nix. "And not a lot of runs inside like a lot of people tried to last year. They try to go outside. We have to adjust to that. We'll play better with it as the season goes on."
That will likely be the case again Saturday night vs. the Sun Devils, an up-tempo spread offense that features the read-option while being blessed with a running back, Marion Brice, well-versed in the passing game.
Yes, it appears another instance of horizontal stretching will test the already shaky depth of Notre Dame's depleted defensive line, including starting sophomore end Sheldon Day, out the last two weeks with a high ankle sprain.
"We're trying to give them as much of a blow as we can, but we also feel like we're a better defense with those guys on the field," said Kelly of the starters. "You're in kind of that 'When do you take them out and when do you put them in?'"
Dance With Who Brung YaRegardless of the rookie duo's pending contributions, expect Tuitt, Schwenke, and Nix to do the heavy lifting.
"That's something I've been working on for awhile," said Nix of his projected and since-realized increase in work volume. "Since spring football we talked about me staying on the field more, going from like 40-50 snaps to about 73 the last game. A lot of improvement with the loss of weight and my conditioning."
(Asked for his current weight, Nix noted, "I don't like to tell people. It's definitely not 357.")
Regardless of where he tips the scales, Nix played last week's 72-snap marathon without a loaf, a statistic tracked by the staff since Kelly's arrival.
"I usually don't have that many but with 72 (snaps) for a big guy, having zero was real nice," Nix noted with pride. "I usually have maybe one. None? I was surprised. We looked at the film and I was happy about the loaf part, but my game-play can get better.
"I feel good no matter what," he continued. "I do my best to run to the ball every play. People try to get it out fast but I feel great no matter what. Even if I'm winded or about to pass out. That's my DNA man, that's what I do."
It's not, however, something his designated backup on the nose, Schwenke, is used to.
"There is a learning curve because the responsibilities change quite a bit," said Kelly of Schwenke's play at end in relief of Day the last two weeks. "I thought he's done a pretty good job. We had some missed assignments for him, and here's the biggest difference: The volume. His volume jump was huge, and then you're getting tired. We've got to get him out. We're getting less productivity, so I think that's been the biggest jump.
"He's been able to settle into the role relative to what *we're asking him to do, but we have to be much more careful with the amount of reps that he's getting. That's probably been the biggest concern."
(*Of note, it was Schwenke whose push through the Sooners right side allowed the Irish defense to stifle a 4th-and-1 run by Oklahoma quarterback Blake Bell last Saturday.)
Spelling Schwenke as well as starting Cat linebacker Prince Shembo will be Williams, a player whose work load was expected to increase, but has done so exponentially due to Day's aforementioned injury, the loss of steady defensive lineman Tony Springmann in August, and inexperience among the remaining backup ranks.
"He's playing much more than he's ever played, and he's obviously playing in our nickel package as well as he's getting some reps in at the defensive end position," said Kelly of Williams. "He's taken Shembo's reps and he's taking Kona's reps when he goes in. So one of those guys is out, generally speaking, when (Williams) goes in, unless he's in nickel, and then he's taking Kona out and then Prince is in the game (as well)."
All of which will prove crucial to Saturday night's outcome.