Analyzing the Huskers Halftime Adjustments

“How well have Frost’s teams been able to adjust at the half?” This is a question I have been asked on Twitter and Reddit. For me, its been a point of frustration watching the Huskers the last three years. To get a better feel for what is going on, I wanted to look at how Nebraska has played the last three years between each half using EPA.

To do the analysis I am focusing using total expected points added or TEPA. Expected points added divides scoring credit across all the individual plays rather than just scoring plays. One way to think about EPA is this: the 50-yard play that ends at the one-foot line did more to set the team up to score than the QB sneak that gets the points. EPA would divide the credit for the TD across the two plays. Total EPA is just the sum of all the individual EPA scores. I also filtered the plays to exclude garbage time to get a better idea of how the game is going when both teams are still competing to win. The variable I am analyzing is the difference between the first and second half TEPA.

Offensive TEPA between halves

Using a t-test we can compare the TEPA difference between wins and losses. In games Nebraska wins, the offense is better in the first half compared to the second half by about 4.8 expected points. Frost’s offenses are better in the second half of losses by about 3 expected points. However, this difference is not statistically significant (p-value = 0.11). On defense, the Blackshirts perform better in the first half by almost 9 expected points in wins. Like their offensive counterparts, the Blackshirts play better in the second half of wins by 2.6 expected points. This time the win-loss TEPA differential is statistically significant (p-value = 0.007).

Defensive TEPA between halves

In Frost’s 29 games at Nebraska, the Huskers have held at least a share of the lead at half 14 times. In six of these games, Nebraska has gone onto lose – 2018 and 2019 Colorado, 2018 Ohio State, 2019 Indiana, 2020 Northwestern, and 2020 Iowa. The 2020 Northwestern game was the only game in which the offense did better in the second half despite blowing the half lead. In only one of the blown leads, 2019 Indiana, has the defensive TEPA improved after the break. However, both halves of that game the Blackshirts had a positive TEPA (lower is better with respect to the defense).

Offensive TEPA by Half

The Husker’s have trailed at the half in 15 games over the last three seasons. They have only been able to get the win in twice in these contests. The 2018 Michigan State game had the Huskers play two bad offensive halves posting a negative EPA in each half. The Blackshirts posted a large negative EPA (-13.8) in the first half of that game allowing them to come back in that game. The Huskers 2019 comeback against Illinois featured 9 expected points added in the second half helping them overcome two bad defensive halves.

Defensive TEPA by Havlf

Only twice at Nebraska has Frost had what I call a “complete game”. This is two halves of good total EPA. A good EPA is positive for the offense and negative for the defense. The first game was in 2018 against FCS Bethune-Cookman. The second was the 2019 blowout win against Maryland. Conversely, Nebraska also played in two games that were the opposite of this: 2018 Wisconsin and 2020 Illinois.

With a small sample size in statistical terms, Nebraska seems to do better when it can jump out to a strong first half. In games where Nebraska trails at half, Frost’s teams do better in the second half. However, its too frequent that the team played poorly enough in the first half that improvement is inevitable rather than enough to get a win. I’ll have more to say on this topic throughout the offseason.

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