During a football match, it is not uncommon to hear analysts and commentators speak of “the number of boxeswhich is often cited to describe the number of defensive players lined up close enough to the line of scrimmage where they can directly impact the opposing running game. The more bodies in “the box”, the more resources the defense has allocated to stop the run.

However, Zach Binneyassistant professor at Emory University’s Oxford College, recently noted that box count isn’t just a function of run defense – it’s actually strongly correlated with offensive personnel, because more training tight with more tight ends or running backs would naturally lead to more box defenders to account for.

Additionally, the defense could use more or fewer men in the box depending on the strength of the opposing attack. and their own defense capability.

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Data from 2015 to 2021 suggests there is not much correlation between achievement expected points added (EPA) and the number of boxes and a weak correlation between the number of boxes and the precipitated EPA.

However, as noted above, the number of boxes correlates strongly with the offensive formation, which must be taken into account. To accurately assess the true effect, three things need to be considered:

  1. Offensive formation and its effect
  2. The strength of the attacking team and its effect
  3. The strength of the defending team and its effect

To examine the effect of the offensive formation, we can create a simple model consisting of situations such as down, distance, and player location on the formation.

Since the predicted number of boxes correlates well with the actual number, the model can capture some effect on the number of boxes:

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