In other musings, I explored what effect offensive balance has had on Notre Dame's football fortunes since 1960. In that 42-year stretch, Notre Dame has won a little over 69% of its games, which translates to 8.37 wins per 12-game season. N.D. during that stretch has usually averaged at least 4 yards per carry (30 of 42 years) and usually averaged at least 7 yards per pass attempt (26 years of 42). (This last year's numbers of 3.9 per carry and 5.1 per pass attempt were among the most pitiful in N.D. history). The combination of those two relatively modest thresholds — 4 yards per carry and 7 per pass — were enough to elevate N.D.'s fortunes considerably. In those years where the squad met both thresholds, it averaged 9.4 wins per 12.

I decided to look to see whether the same kind of effect could be observed on defense. Part of this was driven by my initial concern that Willingham was too preoccupied with offense and too unconcerned with defense to be successful at N.D. Once again, however, a close examination of the numbers revealed some pleasant surprises. Stanford was actually a pretty good defensive team last year, holding its opponents to 3.53 yards per carry and 6.98 yards per pass. Those figures were quite similar to N.D.'s this year, which were 3.50 per carry and 6.93 per pass. As we'll see, those numbers are good enough for a reasonable level of success at N.D. in most years. An improvement of a quarter yard per rushing play and/or a yard per pass might produce some dramatic improvements, however.

Once again, I broke down the years by rushing and passing yardage (this time yardage allowed per play) and then averaged the season records and projected them to a number of wins per 12 game schedule. Here are the results:

Rushing yards per play allowed

2.75 or less:      9.9
2.76 to 3.24:     9.0
3.25 to 3.75:     6.9
3.76 or more:    7.2

Passing yards per play allowed

6 or less:       9.6
6 to 7:           6.9
7 to 8:           7.6
8 or more:     6.8

Interestingly, both defensive statistics break down as indicators, by themselves, past a certain point. For rushing it's about 3.25 yards per carry and for passing its about 6 per pass. But let's consider what happens if we look for correspondence between them.

Let's consider first a very modest constraint: years in which N.D. has held the opposition to 3.75 yards or less per carry AND held the opposition to 7 yards or less per pass. There is nothing remarkable about either of these levels. N.D. has held the opposition to 3.75 or less per carry in 37 of the 42 years (Davie has the unusual honor of having missed this target in 2 of his 5 years: 1997 and 1999). N.D. has held the opposition to 7 or less yards per pass in 35 of the 42 years (you-know-who also missed this one twice: 1999 and 2000 -- Faust, by contrast, never missed either of these levels in his 5 years). The correspondence of these two levels takes N.D.'s win rate to 8.53 games per 12.

Suppose we were to turn it up a half-notch and look at years in which N.D. has held the opposition to 3.25 yards or less per carry and 7 yards or less per pass. Now the win rate starts to look pretty good: 9.6 wins per 12 games. While neither the N.D. nor the Stanford defense were quite there last year, they weren't far away; both teams held opponents well below the national average of 3.9 yards per carry.

If we move the dial one more click to years in which N.D. has held the opposition to 3.25 or fewer yards per carry and 6 yards or fewer per pass, the win rate starts to look very good — now it's at 10.3. In fact, at these levels, we start to see the formula for a national championship. There are some very familiar teams on the list of defenses that have accomplished this feat: Ara's 9-1 1964 team, his 1966 national championship team, his 1970 Cotton Bowl champion, his 1973 national champion team, his 1974 Sugar Bowl champion team, Devine's 1977 national championship team, Holtz's 1988 national championship team and both of his #2 teams: 1989 and 1993. No team N.D. to achieve these thresholds have ever finished worse than 8-3. No Faust or Davie team appears on this list. Both of Davie's 3-loss teams were essentially flukes that unfortunately prolonged his career.

Statistically, N.D.'s defense was good enough to be competitive last year, the poor record was apparently mostly a function of terrible offensive play. A modest improvement in run defense would get it to the point that (if matched by a reasonable offense) would probably put it in reach of a significant bowl game. A significant, but not outrageous, improvement — particularly in pass defense — would be necessary to bring a national championship into view.