I try my best to be a tape-grinder, analyzing film to inform my opinions regarding a team or player. However, given the moratorium on college football film, it is challenging to locate film for Boston College’s defense in 2021. I could watch the broadcast copy. However, the broadcast angle’s limitations on defense are more pronounced than the ones on offense. This article dissects Boston College’s defense from a statistical and analytical perspective.

In this article, I use data from Sports Info Solutions (“SIS") and Pro Football Focus (“PFF”). SIS’s statistical portal provides excellent data regarding a team’s tendencies and usage of various personnel, formations, and alignments. Most people know PFF for their grading of players, but PFF also has excellent statistics for individual players.

Last time, we discussed the BC defense’s formational tendencies from 2021. As with most teams, the Eagles primarily use their Nickel personnel. However, one major tendency change from 2020 to 2021 was the diversification of the defensive personnel groups within the major families. As the coaches became more comfortable with the players and those players became more familiar with the scheme, the coaches expanded the types of personnel groups they put on the field in Nickel and Dime.

This article will look more at alignment tendencies. These numbers dive a little deeper into how the defense looks before the snap. Whereas the offense typically dictates what type of personnel the defense uses on a snap-to-snap basis, these pre-snap tendencies force the offense to make decisions about which matchup they want to attack. The location of the safety can influence which direction the offense wants to run, whether the quarterback hands the ball off or keeps it, and where the QB wants to throw the ball.

The “box” describes the area from the line of scrimmage to about five yards past it and from one end of the offensive line to the other. The latter part naturally has more flexibility to include most edge rushers. The number of men in the box for the defense is an essential variable. This number frequently changes before the snap, as the offense motions their players around the formation and the defense attempts to disguise their play. Furthermore, this number typically helps dictate to the offense whether they run the ball or not.

Despite spending about the same percentage of snaps in Nickel, BC was near the bottom of light-box usage. There are several contributing factors here. First, Hafley and Lukabu most likely felt confident about the secondary being able to handle their one-on-one matchups. Therefore, they felt comfortable moving a safety down into the box. Second, the Eagles’ struggles in run defense necessitated moving another defender into the box to help stop the run. Even when they were in Base defensive looks, BC frequently walked another defender down into the box.

However, there is some even more interesting information to glean from this data. Sports Info Solutions breaks down plays by Run and Pass. Additionally, they also provide a Positive Play %. For defenses, these percentages represent how frequently defenses allow positive plays from the offense. Positive plays are not simply plays that result in positive yardage. Instead, they are plays that result in positive Expected Points Added (EPA). The next three tables will describe how often BC used each type of box count, broken up by play type, along with the rate at which they allowed positive plays from the offense.

Based on this data, we can see that when BC used light boxes, they struggled against the run. Furthermore, when they used seven-man boxes, they struggled against the pass. These numbers are not particularly surprising, especially the former. However, the stacked box numbers, specifically the Passing Positive Play % and Rank, are interesting and surprising. Even though the sample size is small (only 21 plays), the Eagles were above-average against the pass from stacked boxes.

While the box count influences the offense’s decision regarding running the ball, the pre-snap coverage shell identification influences where the quarterback wants to throw the ball. When reading the defense before the snap, the QB tries to identify whether the defense is utilizing a one-high or two-high shell. If the quarterback sees a one-high shell, he can believe the defense is using a Cover 1 or Cover 3 defense. While those two defenses use two diametrically opposed concepts (Man vs. Zone coverage, respectively), they have some similarities. With one-high shells, the outside receivers have one-on-one matchups. In general, the middle of the field between the hashes is covered.

Conversely, two-high shells present a completely different look to the QB. Again, Cover 2 and Cover 2 Man (alternatively, Cover 5) are very different defensive looks. But with two-high shells, there are various holes in the defense over the middle, especially deep. Generally, against two-high shells, offenses will seek to either run the ball or throw it underneath. Against one-high shells, they would prefer to attack deep and outside.

Looking back at the box count usage rates, these coverage shell numbers make sense. BC was near the bottom in the usage of light boxes, indicating they rarely kept both safeties deep. Therefore, it makes sense that they also rarely used two-high coverage shells. Conversely, BC used one-high shells, where one safety was walked down into the box or into the slot, more than almost any other team in college football.

Part of this is due to opponents and the opposing quarterbacks. BC only faced a few quarterbacks last year that could consistently threaten them through the air (Sam Hartman, Devin Leary, maybe Connor Bazelak?). Consider opponents like Louisville or Syracuse; the Eagles were much more focused on stopping the run, as opposed to fearing how the quarterback could beat them with his arm. Granted, they still were lackluster against the run but the strategy and thought process remain sound in my opinion.

In 2022, Boston College does not face many dynamic passers once again. The Eagles will face Devin Leary again but Sam Hartman might still be out due to his recent medical issue. Virginia Tech’s new quarterback Grant Wells was solid at Marshall but could have some growing pains against ACC opponents, especially early in the season. DJ Uiagalelei looked awful against BC last year; Jordan Travis and Malik Cunningham are dynamic rushing threats but still have room to grow as passers. Every other quarterback on BC’s schedule is either a new starter, unproven, or mostly a rushing threat. Expect BC to maintain similar numbers with respect to their coverage shells.

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