Photo Credit: John S. Peterson

Greed Is Good: Previewing the 2021 Nebraska Defense

August 12, 2021

To mark the return of the I-80 Preview podcast for another season, I took this very long preview of Nebraska’s defense and made it a podcast. That won’t be a regular occurrence, but I’ll do it again next week to look at the offense and then we’ll be back to regularly scheduled podcasting––a game/opponent preview––the Thursday before the Huskers take on Illinois on Aug. 28. Point is, you can listen to this article if you want to, and, since I’m only planning to do that once more this year, you could call this a limited edition.

Anyway, subscribe to the I-80 Preview podcast by visiting your local podcast purveyor, subscribe to Hail Varsity here and thanks for listening and/or reading. -BV

The trend is generally, but gradually, upward. We should start there with Nebraska’s defense, which starts the 2021 season with some of the most returning production in the country.

Erik Chinander’s Blackshirts have gotten a little bit better each of the past three seasons. You can see that at the play level. The Huskers’ defensive success rate has improved from 44.9% in 2018 to 43.1% in 2019 to 42.7% last year. That’s simply a measure of what percentage of plays the opposing offense “wins” based on hitting yardage thresholds that vary by down.

You can see the Blackshirts’ progress at the drive level. In 2018 the Huskers’ defense allowed a touchdown on 31.8% of drives. Then it was 26.1%. Then it was 28.6% in 2020, a slight downgrade from the previous season though it doesn’t feel like one given that Nebraska played a conference-only schedule.

Most obviously, you can see it in points, the actual currency of the game. In 2018, Nebraska allowed 34.3 points per game against conference opponents. That improved to 30 the next year and 29.4 last year.

That’s all good for Nebraska. That’s all progress.

But here’s the question and the complication. In all of those categories I just mentioned, Nebraska’s defense went from the bottom-third nationally to about average, maybe a little better. In today’s college football, you can expect the average defense to allow about 28 points per game. Chinander, after three seasons leading the defense, has the Huskers there.

But, in a league where Ohio State does whatever it wants, on both sides of the ball, Penn State tries to keep up by doing the same and the rest of the conference contenders—Wisconsin, Iowa, Northwestern, Michigan, Indiana (at least lately)—tend to win with defense, is simply hitting the national average enough?

With the fifth-most returning defensive production in the country, the Blackshirts should improve again in 2021, but how high is the ceiling?

Here’s a thought experiment. Let’s agree that Nebraska’s defense is gradually improving. Now think of an amount of money that you would not be comfortable losing and then add one dollar to that number just to make it extra uncomfortable. If you had to bet that amount on Nebraska’s defense doing one thing at a high level this season—could be stopping the run, getting off the field on third down, rushing the passer, anything—what is that one thing?

Maybe you had an easy answer but statistically speaking, it’s hard to identify such a calling card from the past three seasons. For this piece, I took 30 defensive categories, dropped them all in a spreadsheet, and then color-coded Nebraska’s numbers based on national rank, dark green for the best in the country transitioning to yellow in the middle then to dark red for the worst teams in the country. (Shoutout to conditional formatting and Microsoft Excel.) Looking at the past three seasons at one time, bands of green would be good, bands of red bad.

There were neither. Instead you had a lot of yellow. A green here, a red there. No easily identifiable pattern, no calling card so to speak.

That’s not necessarily a problem, though I wouldn’t call it ideal either. Nebraska’s defense is, broadly, getting better even if I can’t exactly say with much certainty what it has been great at. But, with this much production returning—three of the top four DBs, eight of the top nine tacklers from 2020—the expectation should be for continued improvement in 2021.

With that as a baseline, and a fairly murky identity beyond, maybe growth opportunities are the way to go. If the Blackshirts continue a gradual upward trend naturally, what are the things that could perhaps jolt them from a reasonable outcome—say, a top 40 defense—to something more unreasonable? And better.

Here are three areas:

No. 1 – Digging In in the Trenches

Nebraska Cornhuskers defensive lineman Ben Stille (95) takes a breather between turn runnign drills during football practice Wednesday, August 4, 2021, in Lincoln, Neb. Photo by John S. Peterson.

There was little reason to expect Nebraska’s defensive line to be better in 2020 than it was in 2019. The Huskers lost three key players up front—Carlos and Khalil Davis, Darrion Daniels—and all three ended up on NFL rosters. The cupboard wasn’t bare. End Ben Stille was effectively a starter, tackle Damion Daniels played a lot in 2019 and the next wave was full of potential, but that was a significant talent drain on the d-line.

Yet, Tony Tuioti’s group posted three-year highs in power success rate, stuff rate and defensive line yards, three measures that, to varying degrees, try to isolate d-line play. The 2020 group didn’t cause as much havoc—pass breakups, tackles for loss and forced fumbles—as the 2019 line did. It was more just stout, and stout is a good thing to be in the Big Ten. It might be a prerequisite.

Team’s ran the ball 54% of the time against the Nebraska defense in 2020, the highest rate yet of the Frost era, yet did so to increasingly diminishing returns. The Huskers’ success rate against the run, 41.1%, was the best of the past three seasons, ranking 51st. That’s still not something I’d be willing to call a trait, but it’s in the neighborhood. Improving by 2 percentage points in rushing success rate would put the Huskers in the vicinity of Ohio State and Iowa from last year. It would take an improvement of 10 points to be close to what Wisconsin, the conference leader, did in 2020 and that’s probably not in the cards. But 2 percentage points? Assuming a similar amount of non-garbage-time rushes as in 2019, the Huskers’ last 12-game season, improving by 2 percentage points would be the difference of stopping about 10 more runs on the season.

But how can flipping 10 rushes from successful to unsuccessful make that much of a difference? Fair question. The beautiful thing about football is that nothing on its own is “the thing.” It’s all intertwined. Stop 10 more rushes and you’re giving your defense not just 10 good plays but an advantage on 10 more plays that follow in terms of down and distance. If you give up explosive plays on all 10 that follow, then it’s all for naught. The point, however, is that those plays should be less likely based on the previous first-and-10 run the defense just stopped for a 2-yard gain.

Think of defensive success rate as starting a boulder rolling downhill. Or, maybe think of it as playing perfect strategy in blackjack, which can be fairly mundane—not making any choices of your own—but it gives you the best chance at success. That type of play should be attainable for this Nebraska defensive line.

Would it be more fun to think about what a really great sack rate would mean for this defense? Yeah, it would. But Nebraska ranked 97th nationally in sack rate last year and if you see any ready-made Randy Gregory’s walking around, let me know. Stopping the run, being sound up front and letting a group of linebackers that Frost himself said “can run” show off that range could offer some pretty big returns.

And it should be attainable for this veteran group on the line. A sub-40% success rate against the run is the goal here and should be a good way to track this defense throughout the season.

No. 2 – Was It the Distance or the Defense?

If three-year strengths are tough to identify with this defense, one of the benefits of such a facet-less improvement is that persistent weaknesses aren’t easy to find either. In 2018, the biggest flaw was an inability to consistently stop the run, but the rushing success rate improved the next year and again the year after. The most glaring issue in 2019 was run stopping in short-yardage situations. That’s a specific scenario, one a defense doesn’t encounter all THAT often, but it stood out. A year later, Nebraska was pretty good when it came time to gut out stops with less than 3 yards to go.

The big problem in 2020 was only there for half of the year. Through Nebraska’s first four games last season, the Huskers were awful on third down, allowing opponents to convert 54% of the time which ranked 100th nationally. Over the last four games, Nebraska allowed a conversion 24.5% of the time, 10th nationally.

What changed? It wasn’t just increased resolve. Not playing Ohio State over the final four helped, sure. In an eight-game season the Buckeyes can wreck some numbers pretty easily. But a more direct answer is that the Huskers started having more success on other downs, namely first down.

Over the first four games, the opponents’ average third-down distance was 5.3 yards. Over the final four it was 8. Proportionally, that’s the difference between having to drive from Kimball to North Platte for a first down, and having to go from Kimball to Kearney. (Yes, I grew up in the Panhandle and all of my references will begin in the West. Deal with it.) The crazy thing about that is Nebraska didn’t really improve that much from a yards allowed perspective on first down, giving up 5.2 yards per play during the bad third-down times and 5.0 during the good third-down times. What did change, however, was Nebraska’s success rate on first down—43.4% over the first half of the season, 33.3% over the second half. The yards didn’t change much as opponents still had some success and hit some big plays when they did, but the frequency changed as the Blackshirts won first down two-thirds of the time over the last half of the season.

Another nice thing about having a veteran defense is this is the perfect time to really try to fine-tune situational football. Every football coach in the world, at every level, stresses the importance of third down because the result—get off the field or stay on it—is binary and just a play away. Nebraska should be in a position to be more abstract than that. Win first down. Take the upper hand. This group saw the rewards firsthand a year ago.

Now is the time to undertake that type of detail work and there are other areas worthy of attention. Nebraska posted its worst points per drive average in 2020 on opponent drives that crossed the Huskers’ 40. Red-zone defense has to start before the red zone, even if all anyone is going to look at is the pretty arbitrary definition of the last 20 yards. That would be a consistent message if I were coaching the defense, which everyone should be thankful I’m not.

The pass defense has to get better, and there’s no reason it shouldn’t given what the Huskers return, both in terms of starters and up-and-comers, in the secondary. Nebraska’s improved success rate with the run came with a steep drop in success against the pass. That can’t be the case again with two starting safeties back along with one of Nebraska’s two best defenders, Cam Taylor-Britt, at cornerback.

The value of experience is not having to start from scratch, as multiple assistants on the defensive side have said throughout fall camp. What happens on third down, what happens when opponents cross the Huskers’ 40 and what happens against the pass are three of the first categories I’ll look at it to determine if Nebraska is getting the most out of what having a veteran defense should offer.

No. 3 – A Difficult Discussion of Luck

I wouldn’t say I have an Ahab-like infatuation with turnovers, but I also have to admit it’s closer to that than it is not infatuated at all. Turnovers are maddening, these random moments of a ball popping out of a running back’s hand or a quarterback throwing it to the wrong team. They occur on less than 1.5% of all the plays in a given season, yet they decide games. They can often be, in pickup basketball terms, next-basket-wins when you’re playing to 11 by 1s and 2s and the score is 9-3. How is that fair?

Nebraska Football Llinebacker JoJo Domann Keeps Illinois from Catch

November 21, 2020: Nebraska Cornhuskers linebacker JoJo Domann (13) keeps Illinois Fighting Illini tight end Daniel Barker (87) from making a catch in the first half at Memorial Stadium in Lincoln, Nebraska. Photo by John Peterson.

It’s not. And neither are turnovers. You can’t really control them, at least not in any replicable way I’ve been able to find, yet they are reality. And the reality here for Nebraska’s defense is they’ve earned more than they’ve gotten the past three seasons.

Over that stretch, the average defense has recovered an opponent fumble 49.7% of the time, which makes sense because that’s what that number always is—right around 50%. Fumbles being coin flips, on a large scale, is one of the inalterable truths of the game. Over the past three seasons, Nebraska’s has recovered 40.4% of opponent fumbles, or 5 fewer than expected over 32 games. Most of that total came last year when NU opponents fumbled 13 times and Nebraska recovered two. That’s 4.5 recoveries below expectation, which might have a pretty big impact in an eight-game season.

Interceptions are similarly steady as a function of passes defended—the number is about 20% each year. The Huskers are at 17.4% since 2018, or four interceptions off the expected pace. Nine total takeaways in the hole may not seem like a lot over three seasons, but then again more than half of Nebraska’s 32 games under Frost have been one-score games so you’d rather have them than not.

Those turnover numbers, while steady on a national scale year to year, are bouncing all over the place at the team level. The 2017 UCF defense recovered 70% of opponent fumbles and 28.6% of its passes defended were interceptions. For the season, the Knights had 32 takeaways against an expected total of 22.5. Special seasons are made that way (though having an offense that averaged nearly 50 points per game helped, too).

So what are the 2021 Blackshirts supposed to do to end up on the lucky side of the ledger? There isn’t much they can do that they haven’t been doing. In 2018, knowing teams can’t just “go get more turnovers,” I started looking to see if there is a correlation between creating takeaway opportunities (forced fumbles plus passes defended, TakeOpps for short) and actual takeaways. It’s there, though it’s only good to a point. About half of a team’s takeaways can be explained by its TakeOpps. In yet another turnover number that remains stable year to year, over the past five seasons it has required 3.4 TakeOpps on average to produce one takeaway.

In 2018, the Huskers ranked 10th nationally at 6.8 TakeOpps per game and 36th at 1.7 takeaways per game. 2019 remained strong—18th at 5.9 TakeOpps per game and 18th at 1.8 takeaways per game. 2020 wasn’t so strong. Nebraska’s TakeOpps dropped to 4.6 per game (81st) and its takeaways to 0.9 per game (109th). Still top-20 in two of the three years is a pretty good indication of how this defense is built and if that’s not enough, revisit Chinander’s description of modern-day defense before he’d even coached a game at UCF in 2016: “In this day and age of the way your offensive football is going, the way to win games on defense is sacks, plus turnovers, minus explosive plays. We have to be aggressive, we have to take some chances.”

The Huskers’ haven’t checked the sacks box yet, and limiting explosive plays has been a mixed bag, but they have created the opportunities for takeaways. Now they just need to, you know, get what they’ve earned one of these seasons. Getting way more than they earned wouldn’t be out of the question given nearly two decades of particularly bizarre turnover behavior impacting the Huskers.

Does experience make a team luckier? I’ve never explored that, but I’m still pretty comfortable saying, “no.” Turnovers don’t work that way. In fact, they don’t really “work” any way. They remain random. Creating more takeaway opportunities helps a little.

Playing with a lead helps a little because teams that trail throw more often, leading to more potential interceptions. Sadly, there’s no magic wand for that. It’s not like Nebraska’s been trying to play uphill for much of the past three seasons while looking at a deficit on the scoreboard, though that’s what has happened.

A particularly active secondary also helps a little, again because of interceptions. Nebraska has the potential to check that box in 2021 at least.

But beyond that, we’re just waiting for the coin flips. It’s not a discussion I like, you like or coaches like because there’s not much anyone can do to control this part of the game.

Experience probably doesn’t generate luck, but it does at least afford the luxury of talking about it.

Let’s go back to that uncomfortable amount of money I asked you to metaphorically put up at the start. But instead of betting it, let’s invest it. If you could buy into a few defensive categories this season that would maximize your return at the end of the season—i.e. produce the highest rated overall defense—what would they be?

I’d put the largest share of my metaphorical money on the run defense, as measured by rushing success rate. Nebraska has a defensive line that, just recently, showed it’s capable of doing that at a level that holds up in the run-stoppingest conference of them all.

I’d hedge that with a small buy in the secondary’s ability to be a high-havoc rate group. That one is a bit more of a gamble based on the most recent results. It’s less of a play on what will happen and more of a play on what needs to happen, especially if the run defense is strong. The Blackshirts will see more passes in 2021 if that’s the case.

Nebraska has two super seniors at safety. It has a potential star at cornerback. It has good young talent and a great position coach to fill in and strengthen any gaps. That group has the potential to be an active unit with a lot of pass breakups, which, theoretically, is a good way to put yourself in position for interceptions. If the rush defense improves to, say, a top-40 level and the pass defense comes back closer to average, I’d feel pretty good about my Blackshirts portfolio. That would be a defense that was close to achieving what it probably should with so much experience back. It’s a defense I’d put in the 24 points per game range, and you can win some games with that.

I won’t be putting any of my money on the turnovers portion of this discussion, though if you’re looking for an unlikely get-rich-quick scheme, throw it down on the Huskers averaging more than 2 takeaways per game. It’s going to happen one of these years, and, if it coincides with a year when the offense finally eliminates some giveaways, watch out. The Gameday crew will be talking about how an 8-1 Nebraska is back and in the Playoff discussion. If that record is largely based on turnovers, it probably won’t be true (or at least not sustainable), but that happens all the time with breakout seasons.

Still, that’s too random for my blood. My metaphorical money goes to more consistent parts of the game and if experience doesn’t get you that—consistency—what’s it really good for?

Big-picture, the Blackshirts are a good bet to hold up their end of the deal this season. The offense? That’s a more complicated discussion, one we’ll have next week.

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