DEFENSIVE RECAP: 2023 Iowa
Pull yourself away from googling 'dylan raiola nebraska huskers' for 10 minutes to read the final game breakdown of the 2023 season
Glossary of Terms1
Link to Charting Sheet2
The Nebraska offense played one of its worst games of the season against Iowa with a bowl on the line, but you cannot say the same for the Blackshirts: In the biggest moment of the year, NU’s 2023 defense put on one of its best performances. That Nebraska is home for bowl season has nothing to do with defensive coordinator Tony White or his crew.
The raw point total wouldn’t necessarily indicate that: NU gave up 10 points in the first half to an offense that by many advanced stats could be considered one of the worst a Power 5 conference team has ever fielded (and would have given up more if not for two blocked field goals), then gave up a back-breaking explosive run on a must-stop drive that set up the winning Iowa field goal.
But the underlying data presents a different picture: Iowa’s offensive success in the first half largely came on some pretty unsustainable third down conversions and field position. On 32 first- and second-down snaps in the first half, Iowa produced only eight successful plays, a 25% rate. But on third downs, the Hawkeyes went 6 for 12, exactly double the rate of success they had on early downs. Your rate of success on early downs and third downs is usually correlated, so for Iowa to double up its performance had a lot more to do with variance than anything the NU defense was doing wrong. And things normalized in the second half, with Iowa going 1 for 7 on third down plays. Iowa also started its first-half scoring drives on the NU 17, the Iowa 49 and the NU 44, something the defense can’t control. Even with the blocked field goals, the data would say the Blackshirts’ performance was better than the 10 points given up on the scoreboard.
Other underlying data also has the defense’s back: NU overall success rate on the day was 72.7%, the second-best mark of the season behind only the Purdue game. It also gave up only half of the explosive plays it usually allows (4.5% explosive play rate, also the second best mark of the season behind the Purdue game), while also maintaining a season-average level of havoc plays against an offense designed to not generate negatives. Winning down-to-down success 70-30, halving your allowed explosive plays, and still generating your own chaos is about as good of a performance as you can ask of a defense.
From a scheme perspective, White’s gameplan played out similar to the Northwestern and Michigan State games, two other pro-style attacks that wanted to run the ball with heavy personnel and hit shots off play-action and boots: Heavy four- and five-player fronts, heavy use of five and six rushers, and heavy use of single-high safety coverages.
Iowa, though, took that offensive formula to another level: The Hawkeyes were more run-heavy than any team Nebraska has played this year behind only Michigan (pure run calls on 54.6% of their plays) and played with multiple tight ends or backs on the field on 45 of their 66 snaps. I don’t track the offensive personnel of NU’s opponents, but I’m certain that’s a season-high. For context, Nebraska’s offense is very tight-end heavy and still used 11 personnel 57% of the time this year — Iowa on Black Friday was around 30%.
It was an interesting decision by Iowa, as NU’s defense has not been one many teams even attempted to run on. Opponents entered utilizing pure run plays on just 26.3% of snaps, with a horrid success rate of 35.1%. Iowa wasn’t really able to run the ball on NU, either, and was, in fact, worse — a 27.8% success rate for the Hawkeyes on pure runs — but the heavy-personnel-and-run-the-ball decision also probably was more one of necessity than schematics, as Iowa has faced pretty major injuries and lack of talent at the receiver position. Trying to run the ball — even with it not working — and playing with two or three tight ends on the field was probably a better bet for Iowa to move the ball than spreading it out to get pass happy. NU’s performance against the run was also a nice bounce back after a season-worst performance against the run in the previous week against Wisconsin, when Nebraska had just a 44.5% success rate against designed runs.
NU matched the heavy Iowa personnel, as best it could. As a 3-3-5 defense, Nebraska will pretty much always be in a base Nickel look with five defensive backs on the field, but NU also played that base look on 92.4% of snaps vs. Iowa, which was the third highest rate of the season. White only brought the three-corner Nickel personnel in for four snaps, below the season average. Nebraska also played with “heavy boxes” — or one more defender around the tackle box than the offense had blockers for — on 27.3% of its snaps, the fourth-highest rate of the season behind only the Michigan, Purdue, and Michigan State games. White was bringing safeties down from deep to play the run more than he has in any game this season, with NU’s boundary safety (32.8% of snaps) spending more time down in the box against Iowa than all but the Michigan, Northwestern, and Michigan State games, and the Rover safety spending a season-high 61.0% of snaps in the box.
But there’s also only so much a base Nickel defense can do against the level of heavy personnel Iowa was pulling out. While it spent a lot of time in heavy boxes, NU on Black Friday also spent a lot of time in boxes where it was outnumbered, playing a man down in the box on 36.4% of the time, a season high. These light boxes were happening exclusively when Iowa went to “13 personnel” (three tight ends) or “22 personnel” (two tight ends and a fullback), which Iowa did on 30 of its 66 snaps. With your five offensive linemen, and then either three tight ends or two tight ends and a fullback, you’ve now created an eight-player blocking surface. To match, the defense will have to put eight players in the box, a tough ask for a team that is committed to only playing with three defensive linemen. For a 3-3-5 team to match an eight-player surface, in addition to its three defensive linemen and three linebackers, it would need to bring two safeties down to get to a matching eight-player box.
For the most part, White resisted doing this, instead electing to play the eight-player surfaces with just seven — or even six — defenders for most of the game. And it worked. In the 24 situations against Iowa where it aligned a player down in the box, NU was successful on 19 of them, a 79.2% rate, well higher than the season average. A huge part of Iowa’s gameplan was betting it could simply overpower NU’s lighter personnel with sheer numbers of blockers, a move that failed pretty spectacularly. It’s also just a good example of how the 3-3-5 defense and base Nickel philosophy work: Lighter boxes and personnel doesn’t mean less effectiveness against the run if you’re getting penetration and speed to compensate.
While the box count wasn’t always heavy, along the front, Nebraska did spend quite a bit of time in heavier surfaces. NU aligned in a four-player front for 62.5% of its snaps and a five-player front on 26.8% of its snaps. The combined rate of four- and five-player fronts was 89.3%, by far a season high — the season average entering was about 69.8%. NU was exceptionally effective when playing with five across the line — an 86.6% success rate, 25 percentage points better than the season average — but was more vulnerable when playing with four across, which had a success rate of 68.6%. A five-player defensive front forces an offensive line to go one-on-one against defenders with no double teams, and the Hawkeyes’ linemen were losing a lot of these individual matchups when NU went five across. They had more success when NU went four across, when they could more easily generate double teams in the run game — though not much, as a 68.6% success rate is still pretty solid for NU — but I think if you want to criticize one thing White did on Black Friday, it was not using more of the five-player fronts. Iowa showed no answer for them, and for them to be used at half the rate as four-player fronts felt like a bit of a wasted opportunity. Iowa’s long run before halftime and the run to get them in field-goal range on the final drive both came against four-player surfaces.
The other way White stopped the run from the light boxes was through blitzing. NU’s blitz rate was about at its season average — 43.9% — but it had one of its most effective blitzing games of the year. Plays where NU brought an extra rusher overall had an 82.8% success rate; on those 29 snaps, Iowa got a successful play just five times. The success rate for blitzes was the second-best mark of the year (trailing, again, only Purdue). On the 14 plays where Nebraska brought a blitzer through the A gap (between an offensive guard and the center), Iowa had just one successful play. When NU brought five total rushers (including non-blitz plays when NU aligned in a five-player front) it was successful 80.8% of the time, and when it brought six rushers it was also wrecking shop (77.8% success rate).
How White was blitzing was a bit notable, too. White has mostly preferred add-on five-player blitzes this year, but against Iowa he utilized a lot more six-player blitzes, on 13.6% of Nebraska’s total defensive snaps. The season average entering had been under 10%. He also brought more pressure from the edges, with 45.2% of the extra rushers coming through the C gaps (outside the offensive tackle) and D gaps (outside a single tight end). That was the third highest rate of edge blizes on the season, behind only the Northwestern and Maryland games. Iowa’s offensive tackles were weaker players than its interior line, so this was an attempt by White at challenging the weakest link along the line.
From a coverage perspective, we saw a lot of Cover 1 and Cover 3, single-high safety coverages meant to get more defenders in the box to stop the run. NU used Cover 1 (a man coverage, with one safety in a deep zone), on over 54.6% of its snaps, a season high. NU used more man coverage overall (59.1% of its plays) than any other game it played this year besides Colorado. In terms of zone coverages, NU slightly used more Cover 3 on Black Friday than normal, and the increased Cover 1 usage largely came at the expense of NU’s Cover 2, 4, and 6 package.
Also notable was that the game against Iowa was NU’s high-mark for press coverage. At least one receiver was pressed on 75.8% of Nebraska’s snaps, which is not far from three times the season average entering of 29.8%. The next highest rate of press coverage was 60% against Illinois, so this was a major departure.
The high rate of man coverage combined with the high rate of press coverage shows White didn’t really think much of the Iowa receivers or their ability to get open against Nebraska’s defensive backs. In games against teams with strong receiving corps — Colorado, Michigan, Purdue — NU didn’t really use much press, under 20%. And against average teams, he used it on about a third of the snaps. Against Iowa, it was three-quarters of the total plays — he really didn’t feel threatened by those guys.
NOTES
Coming Up Short
Nebraska entered as one of the better short yardage defenses in the country, with a 64% success rate against plays on third- or fourth-down of three yards or fewer. The only team to convert over half of those situations against Nebraska had been Michigan, which went an overpowering 5-for-6 in these short yardage attempts. Otherwise, NU had pretty much stuffed short runs all year.
Until Iowa, at least. The Hawkeyes also went 5-for-6 in these situations, keeping several drives — especially in the first half — alive. Part of it was the heavy personnel from Iowa and the light Nebraska box counts I discussed earlier, but a lot of it was just dumb luck on third downs from an Iowa offense that’s 126th nationally in third-down conversion rate.
A Static Game
Part of the 3-3-5’s overarching strategy is pre-snap movement in the box and in the secondary to generate confusion and mistakes for an offense. But Black Friday was one of Nebraska’s lowest usages of pre-snap shifts and rotations of the season. It entered shifting either its front or rotating its coverage on about a combined 60% of plays, but that number would be under 50% against Iowa. Against an Iowa pro-style run game that heavily uses its own shifts and motions to try and outnumber a defense to a side or at the point of attack, I imagine White wanted to tone down the front movement to avoid getting caught out of position/outnumbered and giving up a chunk run. This is also supported by White cutting the amount of defensive line stunts used against Iowa (7.6% of plays) in half compared to the season average (16.4%). He didn’t want NU defenders running themselves out of position.
PROGRAMMING NOTE: That’s it for the game recaps in 2023! Thanks for reading along. Over the next couple of weeks, I’ll be releasing the end-of-season tendency posts for the offense and defense, with the big charts showing NU’s yearlong numbers for tendencies and style of play. Here’s one example from the halfway point of the season. The yearlong post will compare the numbers from the first half of the season to the numbers of the second half of the season, plus the cumulative total. After that, I’ll be sharing some of the yearlong charting I do with paying subscribers, so they can have all of my data on-hand. Beyond that, I’m taking a wait-and-see approach to any transfer portal moves before evaluating or writing about them. Once it feels like the roster is more solidified and the dominos have fallen, I’ll start digging into that!
Yards Per Play measures how many non-penalty yards NU allowed on a possession divided by its non-penalty snaps. Success Rate measures how often NU prevented a gain of 50% or more of the yards its opponent needed to convert on a first down, 70% or more of the yards its opponent needed on second down, or 100% or more of the yards its opponent needed on third or fourth down. An Explosive Play is any designed run that gains more than 12 yards and any designed pass that gains more than 16 yards. A Havoc Play Allowed is any tackle for loss, sack, fumble, interception, pass break-up or batted ball.