Matt Waite’s Collection of Miscellany - Nebraska’s season long slide on offense

Code

library(tidyverse)
library(cfbfastR)
library(zoo)

plays <- load_cfb_pbp(2024)

nebrollingepa <- plays |> 
  filter(pos_team == "Nebraska") |> 
  mutate(sequential_play_number = row_number()) |>
  select(pos_team, def_pos_team, sequential_play_number, EPA) |> 
  na.omit() |> 
  mutate(cumulative_epa_mean = cummean(EPA))

indrollingepa <- plays |> 
  filter(pos_team == "Indiana") |> 
  mutate(sequential_play_number = row_number()) |>
  select(pos_team, def_pos_team, sequential_play_number, EPA) |> 
  na.omit() |> 
  mutate(cumulative_epa_mean = cummean(EPA)) 

coloradogame <- nebrollingepa |> filter(def_pos_team == "Colorado")
indianagame <- nebrollingepa |> filter(def_pos_team == "Indiana")
ohiostategame <- nebrollingepa |> filter(def_pos_team == "Ohio State")
uclagame <- nebrollingepa |> filter(def_pos_team == "UCLA")

If you’ve been following Nebraska’s football season, you’d be forgiven if you thought it started out great and has slowly driven into a ditch as time went on. Even after a loss against Illinois in overtime, hope remained high.

That is, until the Indiana game. A close loss at Ohio State revived some of that hope, and then a loss to UCLA crushed it.

So what’s happening?

The answer? The offense is slowly getting worse as the season goes on. That almost certainly has something to do with Nebraska hiring Dana Holgerson as an offensive consultant. How bad is it? The team is approaching the point that the average offensive play doesn’t add anything to the final score.

What do I mean by that? There is a metric called Expected Points Added, and every play gets a score. Big plays have higher scores – 4, 5 even 6 points. Your two-yards-and-cloud-of-dust run from your own 15 will get you less than 1 point.

Average them together over the course of an entire season and you can get a sense of an offense. And, at this point of the season, Nebraska needs 10 plays to score a point. Indiana, the surprise team of the season, needs 5.

Here’s a closer look.

This is what Nebraska’s offensive season looks like overall. If you’ve never seen a EPA average chart, the first thing you need to do is ignore the first game. There’s just not enough data and the average flies around. Where it starts to reveal who you are is later in the season, when more data comes in.

Where you want to start focusing is the Colorado game. You can see the glorious first half were the game got out of hand, and the dud of a second half where Nebraska’s offense went to sleep.

Now the disaster at Indiana. Nebraska had 300 yards of offense that day … but that is buried by the 5 turnovers, not to mention going 0-4 on fourth down.

No one expected Nebraska to give Ohio State all it wanted. Vegas thought Nebraska would lose by at least three touchdowns. The offense played better than it had – you can see the line move up a bit – but alas, still a loss.

UCLA was a tale of two halves. The first? Bad. The second? Better, and you can see the season average line curve up for that second half.

Now. Want to be sad? Here’s what Indiana’s season looks like. The Hoosiers are remarkably consistent.

When compared to Nebraska, Indiana started hot and has stayed hot. Nebraska started hot and … didn’t.