Determining whether the Cowboys over- or under-performed in 2021

When talking about under- or over-performing in football, it is primarily in the context of what a player achieved relative to their expectations. Ezekiel Elliott under-performed in 2021, partially due to the injury that plagued his season. Trevon Diggs over-performed with his eleven interceptions. Dak Prescott can fall into either bin based on personal opinion.

However, there is a different method for measuring under- or over-performance. Every team across every sport will experience both unlucky and lucky breaks throughout the course of a season. The difference between football and the other sports is that a small sample size of 17 games means that some teams are luckier than others. There are not 162 games, such as in baseball, where the luck will balance out.

So, knowing that there is a luck imbalance over the course of the season, how did the Dallas Cowboys fair in this department?

The Cowboys over-performed in 2021

Photo by Tom Pennington/Getty Images

In this context, we are discussing luck at the team level. Obviously, injuries, penalties, regression, and improvement are a result of luck. But those could all be individual topics within themselves, and they contribute to how the team does as a whole. Thus, by only looking at the team level it should encapsulate part of the luckiness and unluckiness that occurs at the individual level.

As with any sport, the purpose is to win. Teams attempt to gain yards to score points. Teams attempt to score points to win. Teams also try and prevent the opposition from gaining yards and scoring points for the same purpose. This should not be a controversial statement.

But this purpose is also where luck plays into the equation.

The first step is luckiness in yards gained and yards allowed. From 2010 to 2021, the average team scored one point for every 15.2 yards they gained. Meaning that if a team gains 300 combined rushing and passing yards in a game, they should score 20 points. The same is true for defenses with respect to points allowed. In a single game, this relationship is often imperfect. But over the course of a season, teams should generally score close to what their yardage suggests.

A couple of factors might cause variance in a team’s expected point differential and their actual point differential:

• If a team settles for too many field goals after long drives or they rarely settle for field goals and always get in the endzone (red zone inefficiency or efficiency)
• If a team frequently turns the ball over late in drives or benefits from favorable field position after a takeaway (turnover luck)

Both of these factors tend to regress to the mean over long periods of time. This means that if a team was highly inefficient in the red zone in one year, they tend to improve in that category in the subsequent season. The same can be said for turnovers.

The 2021 Cowboys gained 6,919 yards on offense and allowed 5,951 yards on defense. Dividing by 15.2, this suggests that Dallas should have scored 455 points over the course of the season and allowed 392. But in reality, they scored 530 and allowed 358. So while the Cowboys' point differential over the season was 172, it should have been closer to 64.

This is likely due to the defense stalling the opponents' drives by way of turnover after they had marched down the field. Not only was the offense also gifted with a short field frequently, but they also finished with the sixth-best red zone scoring percentage in football. Both the takeaways and efficiency close to the goal line should come down in 2022. And with the over-performance last season, this might mean a point differential decrease of over 100, or about 5.9 points per game.

But points do not matter if the team doesn’t win. One of the more prominent examples of this is the 2010 San Diego Chargers who finished with a +119 point differential but only won nine games and missed the playoffs. Teams can over- and under-perform in their win total based on the nature of the scoring.

“Pythagorean wins” is a good indication of what the record of a team should be given their points scored and points allowed. This is not a predictive metric but it is a good measure of the luck that a team found given their scoring. In 2020, the Falcons had a point differential of only -18 but still lost 12 games. Their expected wins of eight with only four actual wins is the most drastic difference in the last ten years.

The main reason why there is a difference in predicted versus actual is due to performance in close games. Remember the 2020 Falcons as the team that went 1-8 in one-score games? That is the reason for this difference.

Using the Cowboys' actual points scored and points allowed, they were expected to win 12.2 games. Their actual win total was 12. In reality, Dallas was relatively luck-neutral in close games. They had some close wins in the early part of the season and close losses later in the year.

But instead, what if we use the expected points scored and points allowed? This should give us an idea of what 2022 could look like if the Cowboys played similar to last year but without the luck of turnovers, close wins, and red zone efficiency. In this case, using their expected point differential of +64, they should have won around 10 games.

With the Cowboys over/under for wins next season set at 10.5, there is merit to Dallas regressing to the mean and landing around that number. Dallas was a lucky team last year. This is not a commentary about individual performances, injury, and penalties. All we know now is that if the 2021 Cowboys were to replay the season, the most likely outcome would be ten wins.

But this is not to say that 2022 will be a ten-win season. The entire offseason has been spent changing the personnel on the roster, giving younger players more time to develop, and drafting a new batch of potential contributors. This is not a predictive measure, it’s a reflection of last season.

However, the pill of the 2021 Dallas season is even more difficult to swallow knowing that they over-performed in what many believed was a disappointing year. If the Cowboys want to improve, it is not going to happen naturally. The improvement needs to come at the individual level because they are all out of luck.