When You Want to Be Offensive: Understanding Football Receiving Positions
Introduction
Football, especially at the professional level in the National Football League (NFL), has seen an evolution over the last century to an offensive style dominated by the passing game. While running plays remain a means of moving the ball down the field, the primary style of all 32 NFL offensive units is now the passing game. It offers the dual benefit of increased efficiency for quarterbacks and lower risk of injury for players. As a result, it is now considered vital to acquire a quarterback who can sling the ball with strength and accuracy. It is also imperative to apply strategies for that quarterback in the form of wide receivers, tight ends, and the like. These are important not only to secure catches but also run the ball down the field after the catch and, hopefully, get a touchdown.
Physical measurables like size, strength and speed are a major consideration, but they are only part of the story. The ability of offensive coaches to utilize the skillsets of these players in moving the ball down the field, which calls for creating a diverse array of packages that incorporate different formations and schemes for a variety of route running to get open and gain yards after the catch, is critical. The results of the play calls not only vary by team, but depend on receiving position. Even running backs can be used in catching passes on top of receivers and tight ends.
The objective of this project is to answer this question: How do different receivers compare on metrics that define their offensive performance when it comes to offensive concept and defensive scheme?
Data Background
This analysis is based on receiving play data from the analytics firm Pro Football Focus (PFF) from the 2022-23 NFL season (including both regular season and playoff games). It refers to data tables with overall summary statistics, as well as breakdown by receiving concept and defensive coverage schemes. The data contains aggregate statistics over the course of the season for all players who recorded a reception, so this includes some positions like quarterbacks who don't often catch passes. The data was filtered to cover the three main positions that have the most receiving volume: wide receiver (WR), tight end (TE) and running back (RB).
It's also important to cover what the yardage data points mean. The yards per reception (YPR) measures the average yardage from the line of scrimmage, which is the starting reference point for a football play, to the end of the play that includes not only how far the ball was thrown but also how many yards the receiver gained (or lost) after the catch. The yards after catch per reception (YACPR) is that latter component of YPR that is the average yardage measured from the point of the catch to the end of the play. Positive yardage for either figure means moving the ball forward towards the opponent's end zone, and negative yardage means moving it in the other direction.
Analysis
YPR and YACPR by Position
First we take a look at how YPR is distributed across the league for the 2022-23 season for all receiving players.
Based on these plots, the distribution of YPR across all players is right-skewed. A lot of the higher value outliers came players who got far fewer targets than the bulk of players even though they had high average yardage. Therefore, the median value of 9.9 yards per reception works better as the reference point. With this baseline statistic on hand, now we can examine the distribution of YPR broken down by receiving position.
From these separate boxplots, we see that WRs have the highest YPR at 12 yards, while RBs have the lowest at 7 yards, and TEs fall out around the median value at 9.95 yards. However, given that YPR accounts both for passing depth and yards after the catch, the question is: What does the distribution for YACPR look like by position?
Median YACPR as well as the overall distribution trends in the opposite direction as YPR by position. What this shows is that positions that get the lower median YPR like the RB also tend to get the higher median YACPR. That means that yards after the catch are more crucial to them getting the ball down the field in a passing play.
How can we analyze these two separate data features in a more compact manner to understand how they might be related to each other and to receiving position? We can engineer a new feature by taking the ratio of YACPR to YPR for all receivers. Below is the distribution of that ratio feature, with the resultant dataset filtered to contain values between 0 and 2 in order to omit outliers.
What immediately stands out from this distribution of YACPR to YPR ratio is its bimodality, as there are two distinct peaks. Is there a trend in this feature by position just like there is for YPR and YACPR separately?
Indeed that is the case; RBs occupy a completely different regime of YACPR-to-YPR ratio from WRs and TEs, which also have distinct average ratio values. This tells us that for RBs, yards after the catch consist of a much higher portion of their yardage than for TEs and WRs, who tend to get most of their yardage on average from passing depth, WRs in particular.
Receiving Concept
Next we examine how this metric compares between receiving positions for the two main receiving concepts denoted by PFF, which are receiving a screen pass vs. lining up at the slot. A screen pass occurs when a receiver catches a lateral throw made behind the line of scrimmage and then tries to run the ball forward. When the receiver lines up in the slot, that means he is on the line of scrimmage between the outer offensive line and the other receiver lined up wide by the sideline. That means he can run forward at the snap and try to make a catch over the middle of the field. Both concepts can be useful in different situations, depending on the yards needed for another first down and how the defense is set up.
Below are plots showing the correlations between the YACPR-to-YPR ratio and YPR by concept for all players.
While screen plays don't show much of a correlation, we do see a negative correlation between YPR from the slot and the YACPR-to-YPR ratio that also shows a clear distinction between RBs and the other two positions. This means that when a player lines up in the slot, the position he plays may determine how many yards might be expected to be gained. WRs and TEs can catch further up the middle of the field given their great abilities to get open in coverage, so they don't have to accumulate additional yards after the catch to keep the drive moving. RBs, on the other hand, don't necessarily have the same skill set in terms of making catches in defensive coverage like WRs and TEs do, but they can still make shallow catches from the slot and then run for more yards with their speed and agility.
Receiving concept can also have an effect on the average depth of target (ADOT), in that players lined up at the slot tend to catch passes thrown forward at positive depth, while screen passes thrown behind the line of scrimmage have negative depth. The question is: Does ADOT by concept also show any correlation to the YACPR-to-YPR ratio?
WRs and TEs lined up at the slot are likely to be targeted at similar ADOT, getting targeted deeper than RBs. When making a screen pass, RBs get targeted further behind the line of scrimmage than TEs, who in term get targeted further back than WRs. How does this inform offensive play calling?
A slot concept can be called based on how many yards are needed to either score or get a first down, and based on what passing depth the defense might allow, the coach can determine which position might be best suited for the play. Screen passes, on the other hand, aren't reliant on passing depth but rather on the yardage gained in the play. In those instances, a RB can be especially valuable because of their speed and elusive abilities, so they can make the catch further behind the offensive formation than WRs or TEs but still be trusted to keep the drive moving, especially on short yardage downs.
Defensive Scheme
Next we take a look at how different receiving positions do against the two types of defensive coverage schemes, which in PFF are denoted as man and zone coverage. Man coverage entails each receiver being shadowed by one defensive player downfield while the defensive line and even linebackers rush towards the quarterback to create pressure and disrupt the play. Zone has each defensive player in the secondary and linebacker group focus on a specific zone, whether deep downfield or near the line of scrimmage, in order to either stop a running play or rule out passing options for the quarterback.
There are two key terms to understand about receivers playing against passing defensive schemes. One is route running, which entails receivers making sharp and timely cuts in very precise directions downfield in order to get open for a catch. The other is contested targets, which means throwing passes to receivers who are in tight catching windows that can result in forced incompletions or even turnovers to the other team. Both concepts involve receivers getting open to make a catch, so the question becomes how route running affects contested targets for different receiving positions.
The question now is: How do different receivers that are meant to catch further downfield, namely WRs and TEs, compare in terms of contested targets per route run? This can help determine which positions might overall have the most efficient ability to run routes and earn more contested targets based on the defensive scheme. For this, I calculated the contested target to route ratio and plotted the distribution of that feature for each position separately by man and zone coverage.
We can see that for WRs, their advantage in getting more contested targets per route run in man coverage compared to zone is starker than that for TEs. This is likely attributed to WRs having more speed and agility than TEs and hence being more able to get in a position to get a catch, especially deeper downfield where the chances of the targeted getting contested are higher.
Conclusions and Future Work
The following conclusions can be drawn from this analysis:
- The three different receiving positions compare differently in terms of how they contribute to average YPR through YACPR, with RBs on average getting a higher portion with YACPR than TEs, who in turn get more than WRs. This illustrates how WRs and TEs are more reliable on long yardage plays that require targeting them deeper, while RBs can be utilized on short yardage plays that they can get more YACPR on.
- When looking at the receiving concept, WRs and TEs get targeted deeper than RBs from the slot. With that said, RBs have value in catching screen passes that they catch further behind the line of scrimmage and can still convert to productive plays, especially on short yardage.
- In man coverage, WRs get a higher rate of contested targets per route run than TEs, while in zone coverage neither position has a significant advantage. This highlights the importance of developing fast and elusive WRs against equally physical defenses, even if TEs can play a good role from the slot.
For future analysis, it can be helpful to take the following steps:
- Incorporate QB statistics to determine how receivers do with various passer types.
- Include trend of statistics for receivers over course of season to analyze fluctuation from mean.
- Analyze quantitative performance of receiver positions based on different types of man and zone coverage, as well as against defenders with different qualities, using data from sources like AWS NextGen Stats.
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