(A Brief) DEFENSIVE RECAP: 2023 Purdue
Much like Hudson Card I am throwing up something mediocre and late
Glossary of Terms1
Link to Charting Sheet2
PROGRAMMING NOTE: Apologies for the delayed and short post; I had a work emergency in the middle of the week at my IRL job and didn’t have much free time for the defense beyond just charting the game. But I wanted to get some breakdown out, even if it isn’t the normal format and comes only 14 hours before the next kickoff. Sorry!
The Blackshirts on Saturday set several high marks against Purdue, both in performance and in some schematic tendencies.
First, this was the best game this season for the defense in terms of overall success rate, at 73.7%; the previous high had been last week’s 68.9% against Northwestern, and the season average entering had been 61.5%. Saturday was the Blackshirts’ most efficient performance of the year by a statistically significant margin, and it came against an offense that had at least been decent in some previous games.
But not only was it an efficient game, but it was also one of NU’s best for explosiveness, both in limiting big plays from its opponent and generating them for itself. Nebraska allowed Purdue just two explosive plays on Saturday — 3.3% of its total snaps, a season low by five percentage points and nearly a quarter of the season average of 11.2% entering. If this defense has had one weakness so far, it’s been in being a little leaky in the secondary and prone to giving up some gashes. But Saturday, it completely put a lid on things in both the run and pass games; outside of the 27-yard completion on the game’s lone Purdue offensive touchdown, Nebraska gave up just three plays over 10 yards, Purdue gains of 11 and 13 yards on dropback passes and a 12-yard run off an RPO. NU also generated its own big plays at a high rate, getting 12 havoc plays, or 19.7% of its snaps. That’s the second-highest mark this season — after last week’s insane performance of 18 havoc plays (29.5%).
Nebraska’s elevated numbers were largely driven by how well it performed on longer yardage and against the pass. The Huskers entered fairly mediocre in situations where they had their opponents in a passing down (a second-and-8 or longer or a third/fourth-and-5 or longer) but were dominant in those situations on Saturday, with a success rate of 91.0%. That was a season-high by over 15 percentage points; their previous best performance in long yardage had been against Louisiana Tech. That’s also reflected in how well they performed against pure passing plays, successful on 75.9% of Purdue’s designed dropbacks, also a season high, by about 10 percentage points. The run defense has been the star this season, but we’re seeing the pass defense start to come around the last several weeks, too: Since a couple of bad performances against dropback passes against Colorado (56.5% success rate) and Michigan (26.7%), NU has now run off three straight performances of 65% or better success against dropbacks. Admittedly against some pretty bad offensive teams, but still. Also of note from Saturday was that Purdue was the most RPO heavy team Nebraska has played this year by a large margin, with the Graham Harrell-helmed unit utilizing RPOs on nearly 38% of its offensive snaps in a game it spent mostly down at least two touchdowns.
So, how’d Nebraska do it?
Coordinator Tony White threw a major scheme curveball Saturday, playing in almost exclusively four-player fronts. NU entered Saturday using four-player fronts on 31.3% of its non-pressure package snaps, with an additional heavy use of three-player fronts (41.2%) and five-player fronts (27.6%). But against the RPO-heavy Boilermakers, White brought the Jack linebacker down to create a four-player surface on 78.9% of NU’s plays, a truly bonkers number considering the previous high-water marks for four-player fronts had been against Michigan (41.7%) and last week against Northwestern (49.1%) — Saturday was nearly 30 points higher than both. My guess is White — with Purdue using so much optionality with the RPOs — wanted more bodies at the line of scrimmage to combat the running game and force the ball into pull reads from quarterback Hudson Card, either for him to run himself or throw out into the flats, while also keeping at least a couple players at the second level. That’s also reflected in Nebraska’s box population data, with White using heavy boxes on 36.2% of Nebraska’s snaps. That number trails only the Michigan game (42.9%), when he was truly just throwing bodies into the spine of the formation as sacrifices in an attempt to stop Michigan’s efficiency.
White also delivered the season’s best performance by incorporating more motion to the structure of the defense both pre- and post-snap. Nebraska shifted its front shell before the snap more than it has in any game this season, on nearly half its plays, at 47.5%. Its previous season high had been 45% against Illinois — another RPO heavy team. White also used stunts or games on the line at a season-high rate, on 25.4% of Nebraska’s plays, 12 percentage points higher than its season average. Taken together, these two data points give us a window into his gameplan against the optionality of the Boilermakers: If Purdue was going to read the defense so much, let’s make it hard on them by aggressively changing the locations of players in the front and which directions they’re going to go to make those reads harder.
Here’s one example:
Nebraska starts in a 5-2 shell, a five-player-across Bear front with the Jack and Will linebackers walked down to the line and the Mike linebacker and Rover safety filling in behind as the second level. It’s a standard look Nebraska’s run a ton this season. But just before the snap, the walked-up Will linebacker to the offense’s right drops into the second level, making it a 4-3 shell, changing the look and read just before the quarterback is about to be forced to make their RPO decision. Then after the snap, the Rover safety, Luke Gifford, blitzes off the other side, from the offense’s left. Because of all the movement, Card never sees Gifford coming down and hands off to the back running going into the pressure for a 5-yard loss. White was doing stuff like this all game.
He also in general upped the blitz rate more than average to throw weird looks at Purdue. It wasn’t quite last week’s blitz-fest against Northwestern — Nebraska brought an extra rusher on 58.7% of its snaps against the Wildcats — but he did bring heat on 36.2% of plays, the third-highest rate behind the Northwestern and Colorado (54.5%) games. But the blitzes got home MUCH more effectively Saturday: NU’s blitz plays were successful at an 85.7% rate against Purdue, compared to 67.7% against NW and 58.3% against Colorado in the other two pressure-happy games. Nebraska was successful on 14 of its 15 snaps (93.3%) where it brought five total rusher (which would include its plays in a five-player front) and 3 of 4 when it brought six total rushers.
With more blitzing did come, as you would expect, more man coverage, with NU’s 44.8% man rate the third-highest of the season behind, you guessed it, Northwestern and Colorado. What zone coverages Nebraska did play were a little different, however. NU’s most-used zone look entering had been Cover 3, at about 30.8%. But it would use C3 at just 12% Saturday, electing instead to crank up the dial on Cover 6. NU entered using Cover 6 on 6% of its snaps, largely a situational thing or curveball White pulled out on passing downs. But the Huskers would play C6 on nearly a quarter of their snaps Saturday, at 24.1%. And it’s a growing trend: White had used Cover 6 — a split coverage where one half of the field plays Cover 2 and the other plays Cover 4 — on just 11 total plays through the Michigan game, but has used it on 25 snaps in the three games since. And C6 has been dominant, with a success rate of 66.7%, the best of any NU coverage. In the second half against Purdue, White used Cover 6 on 12 of the charted 28 plays, including on 5 of the final 7 snaps as he was closing out the game. Cover 6 is becoming a thing.
I also wanted to point out one new pressure I saw Nebraska use Saturday:
The initial setup here is Nebraska’s Diamond pressure package, with the four-player front spread wide over the offensive guard and tackles, with the other two linebacker standing up at the line in the A gaps. Nebraska has mostly blitzed or run simulated pressures out of this look, usually bringing five of the six rushers and dropping a player into coverage, occasionally bringing all six and sometimes bringing four and dropping two.
But what it’s never done is drop almost everyone, which it does here. All but two of the players fall into coverage, putting nine total players into coverage and leaving just two to rush the passer in a “Drop 9” look. This is just the second time this season NU has dropped nine into coverage, but over the last two games, Nebraska’s overall use of the Drop 8 concepts is way down. Nebraska ran Drop 8 or Drop 9 on 26.9% of its overall defensive snaps entering the Northwestern game, but ran it just once against the Wildcats and only four times against Purdue. It was one of Nebraska’s most successful defensive designs — it has a 66.7% success rate on the season — so I have to imagine this was a situational gameplan thing. But still: It’s weird to see one of your D’s best looks disappear in the last two games to the degree it has. Something to watch.
One other note: Personnel-wise, this was Nebraska’s highest use this season of its pass-rush package, at 16.7% of its snaps, though the inflated number largely came late in the game with the big margin. But walk-on James Williams continued to get run in this little grouping situationally, which was good to see.
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.