How an Elite Offensive Line Impacts Rushing Outcomes
Notre Dame’s run game had a brand new look in 2020 with Kyren Williams emerging from relative obscurity to star status and an offensive line that returned all five starters from 2019. By the end of the season Notre Dame had four linemen heading to the NFL with Williams and Jarrett Patterson looking to join them shortly. However, it’s unclear that all these personnel improvements had an overall positive impact on Notre Dame’s running game outside of short-yardage and goal line situations. As usual we’ll be viewing this through the lens of expected points added (EPA), so for an explanation of EPA and all other advanced statistics we use please check out our primer at this link.
After filtering out runs by Ian Book, short yardage plays, and goal line situations, Notre Dame was less efficient running the football in 2020 compared to 2019. These may seem like arbitrary removals, but the goal is to parse the plays down to where the Irish were attempting to run for explosiveness. In short yardage and goal line, the goal of running becomes different: achieve the line to gain (be it the first down line or the goal line). As we will discuss later, running to achieve the line to gain was a much different and improved story compared to 2019.
On early downs, with these above scenarios excluded, rushing declined slightly from 0.02 to -0.05 EPA/rush, although explosiveness did improve (unsurprising after replacing the relatively plodding Tony Jones with a shifty back like Williams). The decline in these situations is not particularly large, but it will be notable for many Irish fans to see Notre Dame did not greatly improve in this area as many said. The run game in most situations was not better than it was in 2019, and it was not adding much offense at all.
However, this changes massively in the “line to gain” situations we described above. Notre Dame went from awful in these situations in 2019 to elite in 2020, and this alone is why the run game went from borderline unusable in 2019 to an average to above average unit last year. The Irish were successful in two-thirds of their goal line and short yardage situations, up an eye popping 25 percentage points compared to 2019. Both the mean and median EPAs massively improved, and all these things combined point to the fact the Irish run game was an unstoppable force in short yardage situations.
To answer why Notre Dame saw an improvement in line to gain situations but not on all other plays, we re-watched all of the running plays from 2020 and took note of how many defenders were in the box (defined as inside the tight ends and within five yards of the line of scrimmage) and how many blockers (linemen, tight ends, fullbacks, and occasionally wide receivers in a position to block box defenders, e.g. not a receiver stance) were in on each play. We found that Notre Dame was far more efficient when the deficit between blockers and box defenders was lower outside goal line and short yardage situations, and that EPA/rush tracked closely with blocker deficit game by game. The success against -2 fronts is only 8 plays, and likely a bit of an outlier statistically.
Our theory here is that in goal to go and short yardage situations Notre Dame’s talent up front took over. You can put ten men in the box to stop the run, but when Notre Dame has so much NFL talent on its offensive line they will reset the line of scrimmage and run for tough yards due to their talent. However, in situations where running for explosiveness is desired, if the opponent puts too many defenders in the box to be blocked it is almost impossible for Notre Dame to gain large chunks of yardage. Put simply, Notre Dame had the talent up front to get two yards in almost any situation by winning the line of scrimmage, but those same two yards are worth far more on third and 1 than they are on 1st and 10.
The Irish got better running the football in 2020 simply off of the strength of their goal line and short yardage running. To see any similar improvement in other areas, the team will have to stop insisting on running into stacked boxes and lean more heavily on play action to keep the defense from committing to stop the run. It may seem counterintuitive but to get more total production out of the run game, the solution is to run the ball less. The added efficiency should more than offset the loss in volume (total plays). The Irish got away with some bad tendencies of running into brick walls in 2020 thanks to their offensive line talent, but 2021 with just one returning starter in Jarrett Patterson working at a new position will likely not be so kind.