Home » Miscellany, Statistics

How Good Are the Irish? A Year-End Defensive Statistical Review

By · January 4th, 2010 · 0 Comments
How Good Are the Irish? A Year-End Defensive Statistical Review

The 2009 Irish offense has been dissected, detailed and summarized. Now it’s time to turn to the other side of the ball.

Many (myself included) believed Notre Dame’s 2009 defense would be a large step forward from a 2008 unit that was below average. The Irish returned a host of starters, an off-season coaching responsibility realignment by head coach Charlie Weis put co-defensive coordinator Jon Tenuta in charge of play-calling, and the personnel seemed to fit Tenuta’s aggressive scheme.

The reality was far different as poor tackling and confusion in the secondary doomed the Irish. The former is both inexcusable and inexplicable while the latter is mostly the result of inconsistency derived from the scheme and coordinator changes of the past four years.

What follows is a comprehensive analysis of Notre Dame’s 2009 defensive unit. Four tables (defensive efficiency, total defense, rushing defense, and passing defense) with 21 statistical categories are listed below with supplementary data used to understand the more subtle factors that contributed to the high-level performance.

For clarity, a detailed description of the table columns can be found here. I highly recommend this refresher in order to understand the data presented below.

This assessment is consistent with previous analyses that benchmark the Irish production against the competition. Please visit here or here for an explanation of this benchmarking process and the benefits associated with assessing statistical production from this perspective.

Definitions and Disclaimers

The following disclaimers and definitions are pertinent to this analysis:

  • Disclaimer: The numbers presented here were taken from the NCAA statistics website and the Notre Dame football statistics homepage and are accurate to the best of my knowledge as of December 14, 2009, i.e. these values do not include any bowl production of Irish opponents.
  • Definition: An explosive—or big—gain is a running play that produces 15 or more yards or a pass play that gains 20 or more yards.
  • Definition: A short yardage situation is any down and distance pair that requires three or fewer yards for a first down.
  • Definition: A medium yardage situation is any down and distance pair that requires greater than three, but fewer than seven, yards for a first down.
  • Definition: A long yardage situation is any down and distance pair that requires seven or more yards for a first down.

Additionally, for reference purposes, the following are links to the statistical recaps for each 2009 Irish opponent: Nevada, Michigan, Michigan State, Purdue, Washington, USC, Boston College, Washington State, Navy, Pittsburgh, Connecticut and Stanford.

No Efficiency To Speak Of

Third down defense was poor despite fairly good situational characteristics while red zone touchdown efficiency was inflated by a handful of games.

Defensive Efficiency

[table id=211 /]

The Irish ranked in the bottom half of the country in two (third down and red zone touchdown) of the three major defensive efficiency categories.

Red zone efficiency ranked 15th, but the performance in this area is largely exaggerated by the few (eight) opponent red zone field goal attempts as the Irish allowed 88.4 percent of all red zone points to come on touchdowns (86th in the country).

The third down woes started on first down where the defense was largely bipolar.

Notre Dame allowed 6.1 yards per snap on 350 first down plays with two or fewer yards surrendered on over 44 percent of these plays. However, 43.7 percent of first down plays generated five or more yards including 43 explosive gains. These big plays accounted for almost 50 percent of the total first down production for opposing teams.

Despite this poor first down play the third down situations were fairly favorable for the Irish. Out of 350 play series, 158 (45.1 percent) resulted in a third down and more than 74 percent of these were medium or long yardage situations that favored the defense.

Normally, this would be a good thing. Outside of short yardage situations the defense gains the advantage on third down. The Irish just didn’t play well on medium and long distance third downs ranking only 65th in third down efficiency despite opponents needing an average of 7.6 yards to move the chains.

Conversely, on short yardage third downs the defense performed admirably, holding their opposition to a 56.1 percent conversion rate and only 47.8 percent on the ground. But the defense struggled with more than three yards to go as they allowed conversions on almost one-third of opportunities and surrendered 14 big plays, 11 of which came through the air.

The most palpable example of this rather inexplicable phenomena occurred against Boston College. Despite an average distance of 9.5 yards, the Eagle offense converted six of their 13 third down attempts as the Irish allowed five passing plays of 20 or more yards.

The red zone touchdown inefficiency was arguably worse and was most deficient in the season finale against Stanford where the Cardinal scored a touchdown on five of their six red zone trips.

Officially, the Irish allowed touchdowns nearly 57 percent of the time their opponents crossed the 20-yard line as 25 of 35 offensive touchdowns (71.4 percent) came inside the red zone. Expressed differently, 18.4 percent of opponent drives resulted in red zone touchdowns.

Three games, however, significantly skewed these numbers.

Whether it was turnovers by the opposing team (Nevada), stout short goal-to-go play by the Irish (Washington), or the opponent’s conservative game plan (Pittsburgh), these three outings substantially bolstered Notre Dame’s performance in the red zone. Excluding these contests, Irish opponents were exceedingly efficient, scoring touchdowns on 81.3 percent of their red zone appearances.

Totally Offensive Defensive Production

Considering the competition, points allowed weren’t that bad, but opposing offenses were very efficient and effective with their yard production.

Total Defense

[table id=212 /]

The total defensive numbers appear poor, but are just about on par with opponents’ yearly production.

The Irish allowed 25.9 points per game and 38 touchdowns on the year, both good for rankings in the middle of the country and the bright spots of the total defense numbers. The highest point total allowed was 45 in the final outing against Stanford.

The majority of the point production occurred in the second and fourth quarters as 166 of 311 points (53.3 percent) were scored in these periods. However, the point per quarter averages—five, 6.8, six, and 7.1 points per quarter—were fairly similar. Points came fairly evenly on the ground and through the air as well as the defense allowed 18 rushing touchdowns and 17 passing scores.

The remaining three touchdowns came via special teams (two kickoff returns) and a Jimmy Clausen fumble recovery by Washington’s Desmond Trufant. Adjusting for these three non-defensive touchdowns reduces the points per game allowed to 24.2 and bumps the points per game ranking about 10 spots.

Additionally, Notre Dame generated positive PR’s in both points per game and touchdowns. While both rank in the middle of the country, the performance came against good scoring offenses.

The preferred method of moving the ball against the Irish was on the ground. The yards gained favored the pass as 57.2 percent of yards came through the air, but this was mostly due to the large per-play averages throwing the ball. The first down production mimics this as more first downs were generated passing (118) than running (103).

The true preference is in the play-calling.

Opposing offenses ran the ball almost 56 percent of the time (430 runs to 341 pass attempts) against the Irish. On first down, a more apt characterization of play-calling preference, opposing offenses ran the ball on nearly 59 percent of plays. On second and third down short yardage situations a run was called 70 percent of the time.

Moreover, only four games (Michigan State, Purdue, Washington and Boston College) featured a pass-first approach by the opposing offense, i.e. greater than 50 percent of snaps were passes. The remaining eight games were characterized by run-first play-calling while three opponents (Navy, Connecticut and Stanford) called runs on more than 60 percent of plays.

Excluding overtime periods, opponent drives averaged 5.7 plays, 34.1 yards, 2:28 in time of possession, and 1.7 first downs. Most drives were rather short as only 15 generated 10 or more plays and only eight lasted five or more minutes. These short drives were largely the result of big plays (see below) that led to quick scoring opportunities.

On the opposite end of the spectrum, 31 of 136 (22.8 percent) drives were three plays and punt while 33.1 percent of drives resulted in scores. Expressed differently, 23 of 136 non-overtime drives (16.9 percent) ended in red zone touchdowns while eight other touchdowns were allowed from beyond the 20-yard line.

But the most deficient statistics in the table above are the yard efficiency and effectiveness categories as the Irish rank 103rd in yards per play (6.2) and 87th in yards per game (397.8). The former is largely due to big plays and the ability of opponents to exploit the Irish secondary with play-action. The season-high in both categories came against USC as the Trojans gained 501 yards at an incredible rate of 8.1 yards per snap.

Can’t Stop Bleeding Yards On The Ground

Against a tough slate of running teams, the Irish did little to impress.

Rushing Defense

[table id=213 /]

Opponents preferred the run because Notre Dame couldn’t stop it, and because they were built to do it. Five opponents—Nevada, Michigan, Navy, Pittsburgh, Stanford—ranked 30th or better in rushing yards per game and all of these teams but Michigan ranked 30th or better in yards per carry. Unfortunately, with few exceptions, the Irish did little to slow these potent running offenses.

The defense ranks 101st in yards per rush (4.8) and 90th in rushing yards allowed per game (170.3), both dubious honors. Excluding sacks, the per-carry average increases to 5.3 yards.

Seven Irish opponents (Nevada, Michigan, Washington, Navy, Pittsburgh, Connecticut and Stanford) exceeded 150 yards rushing. Seven (Michigan, Michigan State, USC, Navy, Pittsburgh, Connecticut and Stanford) opponents also recorded two or more rushing touchdowns.

The last four Irish foes accomplished both of these feats in addition to averaging 5.7 yards per carry (5.9 yards per rush excluding sacks). It seems that late-season fatigue coupled with good running teams spelled disaster for the Irish run defense.

The problem started on first down, but it didn’t end there.

Despite strong run tendencies, opposing offenses averaged 5.6 yards per first down rush and gained five or more yards on 88 of 205 running plays (41 percent). The defense managed to hold opponents to two or fewer yards almost 43 percent of the time, including 27 negative rushing plays, but it was the frequency of the bigger gains that were the primary problem.

Second down wasn’t much better.

Notre Dame allowed 5.2 yards per second down carry including gains of five or more yards on 42.1 percent of rush attempts. Similar to first down, inconsistent play was also evident on second down as the defense was able to hold opposing offenses to two or fewer yards on a good percentage of plays (40.7).

Short yardage situations were also problematic.

Notre Dame faced 89 short yardage down and distance situations of which 62 (almost 70 percent) were runs. These 62 rush attempts averaged 3.9 yards and over 30 percent produced five or more yards. Perhaps most problematic, nearly 60 percent of these short yardage runs resulted in first downs.

About the only bright spot of the running game was holding opponents to fewer rushing touchdowns than they routinely scored and the performance on third and short. Irish opponents called runs on 23 of 41 (56.1 percent) short yardage third downs. Seven of these 23 attempts (30.4 percent) went for negative yardage and only 11 (47.8 percent) moved the chains.

Giving Up Huge Chunks Of Yards Through The Air

The run was preferred, but selling out to stop it cost the Irish dearly down the field and prevented consistent quarterback pressure despite frequent blitzing.

Passing Defense

[table id=214 /]

Because opponents were able to run the ball effectively, they were also able to throw it with great efficiency. The Irish allowed a 58 percent completion percentage and ranked 81st in pass efficiency as opponents that ran the ball the best also generated the highest per pass attempt and completion averages.

Against these strong rushing offenses Tenuta was forced to stack the box to stop the run. The result was vulnerability to the vertical passing game, particularly off play-action. Both directly led to the defense surrendering eight yards per attempt (100) and 13.8 yards per completion (113).

A stronger, more experienced front four would have partially rectified this problem, but poor tackling also contributed to high yard-after-contact production for opposing ball carriers.

Additionally, because opponents preferred the run and made heavy use of play-action, Notre Dame was unable to consistently pressure quarterbacks. The Irish averaged one sack per 17.9 pass attempts (76), with 19 sacks on the year (89). However, five sacks came against Washington State. Excluding this game the Irish notched only 14 quarterback takedowns, one per 22.7 pass attempts. This is especially puzzling given Tenuta’s penchant for blitzing and applying pressure.

But perhaps most troubling was the inability to stop big gains through the air in obvious passing situations.

On third down, opposing quarterbacks averaged 8.3 yards on 104 pass attempts despite being very pass-heavy (65.8 percent third down pass preference) and facing long distances (average of 8.4 yards to go). The result was a 42.3 percent third down conversion rate when a pass was attempted.

Fourth down was even worse. The Irish allowed 9.6 yards per pass attempt despite opponents needing an average of 8.4 yards to move the chains. Moreover, opponents generated 16 explosive pass plays on third and fourth down for an average of 30.4 yards per play.

Performance in long distance situations was more of the same. Excluding first down, the Irish faced 256 long yardage plays of which 153 were pass attempts (59.8 percent). Opponents averaged 7.6 yards per attempt, gained five or more yards 70 times (45.8 percent), and notched 23 big gains that averaged 28.7 yards per play. On these downs, despite needing an average of 10.9 yards to move the chains, 31.4 percent of these pass plays resulted in a first down. On many of these obvious passing situations, confusion in the secondary led to big gains down the field.

The secondary was, however, somewhat opportunistic, notching 12 interceptions (44) on the year. But 11 of these picks came in the first eight games and the defense was only able to force an interception once every 28.4 pass attempts.

Explosive Gains = Achilles’ Heel

As (painfully) illustrated above, big gains were the crux of the issue for the 2009 Irish defense. And they came in all shapes and sizes.

As a whole, Notre Dame allowed 89 big plays that gained 2,321 yards, an average of 26.1 yards per play. This accounted for 48.6 percent of the total production. Expressed differently, 11.5 percent of opponent offensive plays gained nearly half of their yards. Without these plays the Irish defense allowed 3.6 yards per play, up from the 3.3-yard value in 2008.

But the per-game numbers are simply baffling as opponents averaged 7.4 explosive gains and 193.4 big play yards per game.

The most production occurred on first down where 43 of 350 plays (12.3 percent) gained 1,056 yards (24.6-yard average). The Irish allowed 46 explosive plays on the other downs for an average of 27.5 yards per play.


Almost half (47.2 percent) of the big gains came on the ground as Irish opponents generated 42 runs of more than 15 yards.

These 42 plays gained 958 yards (22.8 yards per attempt), good for 46.9 percent of the rushing production and 20 percent of the total offense. Without these big gains the Irish surrendered only 2.8 yards per carry.

Most of the big runs came on first down or medium and long yardage situations.

The defense allowed 24 explosive rushes on first down, at an average of 22.2 yards per attempt. This production was good for 46.2 percent of all first down rushing yardage without which opponents’ averaged only 3.4 yards per rush.

Excluding first down, 14 more big running gains came in medium and long yardage situations. These 14 plays gained 327 yards (23.4-yard average) and produced 40.5 percent of the total rushing production in these down and distance situations. Many of these big plays were the result of Irish defenders blitzing themselves out of position.


The other half of the big play production came through the air as the defense allowed 47 big passes go for 1,363 yards (29 yards per completion). These 47 plays accounted for just under 50 percent of the passing yards and 28.6 percent of the total offense. Excluding these plays the Irish allowed 4.6 yards per attempt and 9.1 yards per completion.

Unlike the big play production in the running game, the explosive gains through the air were fairly evenly split on first, second and third down. However, as detailed above, the most costly big play production came through the air in down and distance situations that favored the Irish defense.

Facing long yardage down and distances, opposing offenses managed 23 big gains. These 23 plays gained 606 yards and averaged 28.7 yards per play. In other words, 40.4 percent of big pass plays occurred when defenders knew—or should have known—that the ball was going downfield.

In Summary, Is There Any Good News?

There is seemingly little good in the numbers above.

Situationally, first down defense was erratic for the Irish. Opponents were able to run the ball efficiently and effectively as well as frequently generate big gains. At times the defense performed well, but inconsistent first down play was a critical element to the deficiencies of this unit as the Irish often faced unfavorable situations on second and third down.

But the Irish also struggled in favorable down and distances. Far too many big plays occurred in these situations due to poor tackling (yards after contact) and confusion in the secondary. The latter problem is mostly attributable to constantly changing schemes and play-calling over the prior three seasons, and was exacerbated by the blitz-heavy approach in 2009.

From a higher level perspective the Irish simply could not stop the run.

A good defense can consistently defend the run with seven defenders, at least against most teams. A weak and inexperienced front four and rather unphysical play frequently forced Tenuta to drop an extra defender into the box.

But even with eight defenders the defense was often unable to slow opposing runners. This resulted in vulnerability to vertical passes, particularly those off play-action, and hampered attempts to pressure opposing quarterbacks.

Perhaps most disheartening was the impact of the Irish defense on the offense. The defense all but forced an offensive game plan with a low probability of success. Moreover, the defensive values above would likely be much worse if the Irish offense wasn’t so productive and if ball control hadn’t favored Notre Dame in almost every contest.

But there is a silver lining—small improvements could lead to dramatically better play.

Not only did the Irish surrender a large percentage of production from explosive plays, they also allowed many of them in favorable defensive situations. Moreover, the causes of the breakdowns are correctable.

In other words, the problems aren’t with personnel. With the possible exception of the front four, the Irish defense doesn’t lack for athleticism. And the young defensive line should be considerably helped by another year of maturation.

The issues are more closely tied to fundamentals and coaching.

The former is easily rectified. If Brian Kelly and his defensive staff focus on physicality and tackling, first down defense will improve and become more consistent and the Irish will surrender fewer big plays.

However, the inevitable change back to a 3-4 alignment will be a tough challenge for a unit beset with inconsistent coaching styles and schemes. This constant change is largely responsible for the confusion that enabled so many big plays and only excellent teaching by the new defensive staff will mitigate this problem.



Enter your e-mail address to receive new articles and/or comments directly to your inbox. Free!


This article is © 2007-2024 by De Veritate, LLC and was originally published at Clashmore Mike. This article may not be copied, distributed, or transmitted without attribution. Additionally, you may not use this article for commercial purposes or to generate derivative works without explicit written permission. Please contact us if you wish to license this content for your own use.