Photo by Aaron Babcock
Nebraska Football

The Stat That Wins 95 Percent of the Time at Nebraska

May 18, 2017
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It was a beautiful day in October, clear, sunny and 71 degrees. Nebraska was undefeated, ranked in the top 10 and welcoming Purdue (3-3) to Memorial Stadium. The game was the last hurdle before Nebraska was headed to Madison for a West Division showdown with Wisconsin, and it wasn't expected to be a very high hurdle. The Huskers were favored by four scores.

Yet Nebraska went into the half down 14-10. The Boilermakers hit for a pass of 44 yards on their second drive, which ended in a touchdown. Two drives later, facing third-and-11 from its own 12-yard line, quarterback David Blough found receiver DeAngelo Yancey for an 88-yard touchdown pass. Purdue had just the two explosive plays in the first half, but both those drives resulted in touchdowns.

The Blackshirts settled in a bit in the second half, forcing a turnover,  getting three fourth-down stops and holding the Boilermakers scoreless. The offense hit for five explosive plays, didn't turn the ball over and the game turned into a slightly mundane 27-14 win.

Two days later, Mike Riley had this to say at his weekly press conference (emphasis mine).

"We were not very sharp early on defense like," he said. "We gave up a 195 yards on the first four series. Two-hundred yards right off the bat in the game, leading up into the first part of the second quarter. After that, on nine drives we gave up 126 yards. So that’s how the game changed. And that’s why our big emphasis, and that’s why I always talk about it, that’s why explosive plays are so huge in football games. I still think turnovers and explosive plays make the biggest difference in winning the game."

When you combine turnovers and explosive plays you get toxic differential, a new wave(-ish) stat I wrote about last week. There's a pretty strong correlation between winning the combined explosive play and turnover battles and actual wins. People seemed somewhat interested in the concept, so I dove into a pile of old media guides.

Since at least 2004 -- that as far back as I looked -- those guides have contained some breakdown of "long season plays." The definition* of "long" in those guides is plays of 20 yards or more, which is convenient because it's typically what I use for my definition of explosive plays. Those numbers aren't easy to come by dating that far back, but with that and Nebraska's game-by-game turnover margin in hand we can see what toxic differential means at Nebraska.

*As football stats continue to evolve can we please come up with a standard definition for explosive plays? Each coaching staff seems to have its own definition, but they're often different. I use 20 yards because that is the data I have access to, but know that a 20-yard threshold probably favors passing offenses. Last year, 9.84 percent of all passes (sack-adjusted) went for 20-plus yards while 4.32 percent of all runs did the same. Ideally we'd find the yardage mark where an explosive run and explosive pass occurred at equal rates, but I don't have the data set to do that so 20 yards is what we'll use. But the point is that explosive plays are one of the most important stats in the game. We should have a definition.

On to the findings.

WINNING PERCENTAGE

The easiest place to start here is with Nebraska's record when it wins the toxic differential, which, again, is just explosive plays and turnovers gained minus explosive plays and turnovers lost. For reference, Nebraska is 108-61 (.639) overall from 2004 to 2016.



When Nebraska has won toxic differential over that span, it has won 94.7 percent of its games. Not bad. You'll take a 95-percent winning percentage.

Look at the two factors independently and a few things emerge. One, Nebraska is 54-4 when winning just the turnover battle, but the bigger takeaway might be that the Huskers have only won that category 34.3 percent of the time since 2004.

Two, the Huskers have been better at winning the explosive-play battle, but based on the numbers that might mean slightly less than turnovers. That makes some sense. An offense can start at its own 25-yard line, hit three straight 20 yards gains and still turn it over on the fourth play from the 15-yard line and get nothing. Turnovers always matter no matter where they happen.

But here's another consideration on that topic. A team can probably control its big-play ability -- through recruiting, scouting and play calling -- more than it can control its ability to force or avoid turnovers, which, despite Nebraska's attempts to disprove this claim over the past 13 season, should be random over the long run.

And if you're wondering which four games Nebraska lost while winning toxic differential, they were 2004 Iowa State, 2006 Texas, 2006 Oklahoma State and 2007 Colorado. Yep, that means that since 2008 Nebraska is 56-0 in games in which it had a positive toxic differential.

The four games Nebraska lost with a positive turnover margin were 2004 Iowa State, 2005 Kansas, 2006 Oklahoma State and 2011 Northwestern. Since 2008, Nebraska is 40-1 when winning the turnover battle.

YEAR-BY-YEAR

Here's Nebraska season-end margins for toxic differential and its two components.



Surprisingly, Nebraska's best toxic-differential season came in 2006. It probably allowed that team to overachieve a bit on its way to the Big 12 title game and a Cotton Bowl appearance.

The 2009 and 2010 seasons were, as expected, also good toxic-differential seasons. Since joining the Big Ten in 2011, however, the Huskers have a pretty average profile. Last season was Nebraska's best in toxic differential as a Big Ten member, a perhaps encouraging sign for Husker fans in 2017 when you consider the makeup of this team. (Assuming Tanner Lee doesn't throw a ton of interceptions and Bob Diaco's defense prevents big plays, two reasonable but far from certain assumptions.)

BY RANKING

What happens to Nebraska's toxic differential against better opponents? It goes down, as you'd expect, but to a degree that's a little shocking. Here's how the Huskers have fared against ranked teams. (Note: I used teams that were ranked in the final poll rather than teams ranked at the time of the game.)



Nebraska doesn't have a positive toxic differential against any segment of the top 25, which is telling and perhaps explains why there are frequent "can Nebraska be elite again?" discussions. The Huskers haven't been over the past 13 seasons against the best teams they have faced.

AGAINST THE SPREAD

Out of curiosity -- and, honestly, a desire to have a database of Nebraska point-spread info -- I decided to check toxic differential against the spread just to see what would happen. This is what happened.



(Note, I removed three no-line games against FCS opponents so the total number of games here is 166, not 169, and used historical spread numbers from GoldSheet.)

Covering the spread is a higher threshold than simply winning, but that's useful as it can serve as a measure of how often a team is performing to expectations (assuming the line is accurate, and, for what it's worth, the Huskers are 82-84 against the spread over that stretch). Since 2004, Nebraska has covered the spread 75.7 percent of the time when winning toxic differential. Winning the turnover battle has been almost as good (73.7 percent), but then again Nebraska has a weird recent history with turnovers.

Also of note as it pertains to the "expectations at Nebraska" discussion. I've often thought that nine wins at Nebraska (and other programs) is really a baseline. Given an average Nebraska team with an average schedule and you can probably start at nine wins based on program history, tradition and advantages.

Since 2004, Nebraska has been favored in 69.2 percent of its games. That averages out to 8.8 games per season.



So what does it all mean? I'll leave you to draw your own conclusions for the most part, but as a tandem explosive plays and turnover margin appear to be pretty powerful, which makes a lot of sense. The problem is that a coach can't really just go out there and say "get more turnovers and explosive plays." That still comes down to execution, talent, coaching and all of the other football things.

What toxic differential might do, however, is alter how we look at football as spectators. Based on this data, there are on average about 13 game-changing plays available to the two teams in a given game. That's 13 plays in a game that, in 2016, included an average of nearly 143 total plays run between two teams.

As football fans we already know that turnovers are important and the 24-yard completion is good (for your offense), but that might be underestimating those plays a little bit. They're not just big plays, they're massive.
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