Digging Deeper Into Shadow Coverage Impact on Wide Receivers

November 23, 2020

Antonio Losada dives deeper into advanced statistics to determine how relevant WR/CB shadow coverages are for fantasy football purposes. Do elite cornerbacks really shut down high-end wide receivers?

If you only play redraft fantasy football, you know that no matter what you have to play your studs week in and week out. That is non-negotiable, and your lineup decisions mostly come down to who to play at lower-level spots such as WR3 or FLEX. If you play DFS contests, though, you know that you have the whole NFL roster available for you to pick within a budget, and therefore your top-tier "replacements" are also going to be studs. That is why paying attention to WR/CB matchups is much more important in DFS than redraft leagues.

While most of the time cornerbacks don't track receivers all around the field--which we come to call "Shadow Coverage"--it happens from time to time, and a wide receiver finds himself facing strong competition for a full match instead of going against different corners on a fairly balanced basis.

If you have read my work in the past, you already know that I have covered WR/CB matchups in a couple of research posts. I tackled these matchups as a whole in the first one, and then focused on shadow coverage matchups and their impact in fantasy football contests. The results and takeaways of that second study were rather sound, so today, with three more weeks and even 10 weeks in the 2020 books, it makes sense to run some fresh analysis to see if shadow coverages are random or not in how they impact wide receivers and their performances. Let's get to it!

Shadow Coverages Through Week 10

The last time we checked on the status of the NFL from a shadow coverage angle, we were just past Week 7. There had been exactly 70 such coverages up to that point, and now, with three more weekends gone and entering Week 11, there have been 29 more instances to make it 99 on the season.

As you see, the average has stayed virtually the same, at around 10 shadow coverages per week of games. The numbers might go up a bit for the home stretch of the season, as there are only two more weeks in the schedule that will feature bye games for six teams (four in Week 11, two in Week 13).

Shadow coverages are nothing new, and they're not an afterthought either, with at least five corners/teams applying them each week this season. In fact, only three of 10 times there have been fewer than 10 shadow coverages popping in that week's games, with the number falling on the higher side (10+ SC) more often than not.

On a player-basis, here are some quick hits through Week 10:

• Up to 48 different CBs have applied SC at least once this season.
• Bradly Roby led all corners in SC through Week 7 with five such games, but with 10 Weeks gone it's James Bradberry (NYG) who leads all cornerbacks at 7 SC so far this season.

• Up to 55 WRs have been shadowed at least once this season.
• Three wide receivers share the lead for most SC faced: DK Metcalf, Mike Evans, and Terry McLaurin.
• The most-shadowed (three times) wide receivers through Week 7 have been Adam Thielen, DK Metcalf, Sammy Watkins, and Terry McLaurin

Fantasy Performance Against Shadow Coverage

As I did in the prior article researching shadow coverage, I will be using data related to the performance of the CBs/WRs exclusively against their assigned pair (this is, the shadowed receiver, or the shadow cover corner). That means that the targets the receiver logged against other players won't be factored into the numbers.

For example, Tyler Lockett scored 53 PPR points in Week 7, but only 26.1 of those came against his shadow-corner that game, Dre Kirkpatrick. I'll be looking strictly at the numbers against the latter, not the overall game performance.

I have plotted the average WR vs. SC-performances from wide receivers this season in the following scatter plot. The two axes represent both the wide receiver performance against shadow corners (vertical axis) and the difference between that SC-average fantasy score and his season-long points per game average (horizontal axis). The circle sizes are related to the number of times the wide receiver has faced SC, from 1 to 5 times:

Things have not changed a lot since the last time we checked, which is good and means the relationship between SC and WR-performance is still related to a very similar degree:

• After Week 7, shadow corners had gotten the best of their assigned wide receivers in 50 of 70 SC matchups (71%)
• After Week 10, 74 of 99 corners (75%) have limited their assignments to score fewer points than their season averages.
• That variation is virtually non-existent but has gone up a bit, showing how through the 2020 season SC is indeed stable and rather impactful on fantasy outcomes from wideouts.
• Only 13 of 55 shadowed receivers (24%) have been able to, on average, outscore their season-average PPG marks.
• If we limit the population to WRs with at least 2 SC faced, the results are still trending the same way: 7 of 28 WRs facing 2+ shadow coverages (28%) have outscored their season-average fantasy points.

This approach gives an absolute advantage to SC corners in virtually 70% of their matchups against WRs, no matter the wideout level. That is the average advantage through Week 10 on a per-game basis, but that might not be the strongest or more sound approach to tackling this data.

Why? Because even on shadow coverage, not every route/target the receivers work through a single game is against his mostly-faced corner. It makes sense, then, to apply a finer level of analysis. I have made the same exercise as above, only now focusing on fantasy points per target, instead of per game. Here are the results:

The balance is much more shared here in terms of who gets the advantage on shadow coverages:

• Up to 22 of 55 (40%) shadowed-receivers (at leas once) through Week 10 have outperformed their PPG/T against such type of defense.
• As the plot shows, though, most of those receivers have been shadowed just once this year, which makes them outliers (Agholor, for example, has only been on SC once and he caught just one pass on one target for a touchdown, clearly skewing the data).
• Applying a 3 SC+ faced filter, the results are way less encouraging for WRs: only 3 of 10 WRs (33%) have been able to outperform their season average PPR/Tgt against shadow corners (Terry McLaurin, John Brown, and MVS).

Once more, whether on a per-game or per-target basis, it looks like there is between a 60 and 70 percent chance of a shadowed corner edging his assigned wide receiver and limiting his fantasy points to a mark below his season average.

What To Trust In Shadow Coverage? Per-Game, or Per-Target Stats?

Here is another plot, now putting PPR/Tgt season-averages (horizontal axis) in all matchups against PPR/Tgt averages against SC (min. 2 SC faced):

The bulk of the wide receivers that have been shadowed at least twice this season fall between averages of 1.5 and 2.5 PPR points per target on the season. Against shadow corners, though, those marks have been limited mostly to the 1.0-to-2.5 range.

• The impact is not too big, but there is a lower upside for receivers facing SC.
• Among all wide receivers shadowed at least once this season, their average PPR/Tgt sits at 1.93 through W10. When facing SC that average drops to 1.85 (95% of their season average points).
• Among all wide receivers shadowed at least twice this season, their average PPR/Tgt sits at 1.94 through W10. When facing SC that average didn't drop at all.

Looking at SC this way, the truth is that shadow coverage seems to have no impact at all on a per-target basis. But as is always the case with corners, and while studying per-target numbers is the proper approach:

Shadow corners (often the best corners assigned to opposing wide receivers) are not targeted by quarterbacks as often as other corners are.

I'm not making that up.

Here are some takeaways:

• Of the 488 cornerbacks to log a defended route this season, only 32 of them have been targeted more than 55 times.
• More than a half, or 17 of those 32 CBs (53%), have never been on shadow coverage this season through Week 10.
• Of the 15 CBs to apply SC, only 8 of 15 (53%) have been targeted 60+ times over the season.
• Of those 8 CBs, only James Bradberry and Carlton Davis (20%) have been targeted 60+ times while playing at least half of his game on shadow coverage.

This is the Myth of the Revis Island, and it is as true as it gets:

It is not that great corners don't put up paltry or low stats, but rather limit receivers so much in volume that their upside gets ultra-limited.

That is why looking at PPR/T is a good way to see how wide receivers perform against SC on a finer level of detail, but how it could also be a little bit confounding as you have to account for a reduced level of targets going their way, and therefore a limited upside for big fantasy scores.

Even if it doesn't sound perfect, when looking at shadow-coverage impact, it might actually be better to look at per-game stats rather than per-target ones.

How Impactful is Shadow Coverage on WRs Fantasy Scores?

Just to close this third column on shadow coverages, I just wanted to re-run the numbers I already explored three weeks ago, just to see how things have varied, if at all. This is how things looked back after W7:

And this is how they're looking after 10 weeks of play:

Shadow coverages tended to kill the WRs upside more often than not (71% of the time) this season through W7. In the 70 times a WR had been shadowed, more than two of each three matches he came out on the losing side of things scoring fewer PPR points that he had through the year on average.

What about the data after 10 Weeks? Pretty much the same, which shows how SC was a thing after seven games, and how it still keeps affecting WRs three more weeks into the season. 75% of CBs got the better of the matchups, wide receivers have slightly increased their levels of performance over their season averages when they face SC, but on average they keep losing 6.5+ PPR in comparison to their PPG season-averages when they lose the matchups, which sadly happens in 3 out of each 4 instances.

Back after W7, and when facing shadow corners, almost half of the population of WRs (44%) had fallen below 5 PPR points, and more than two-thirds of them (70%) couldn't reach 10 PPR points in those games.

Now, after W10, this is how things look in 99 shadow-coverage instances:

Not much of a change. More than a third of WRs (39%) are still falling below 5 PPR against their assigned shadow corners, and 68% fell below 10 PPR points in those games. Only four players (the same as the last time we checked, so no one reached that mark from W7 on against SC) have exploded against a shadower.

Fantasy Relevance

Re-running the analysis on shadow coverage has proved (or solidified) once more how shadow coverage can (and most often does) widely affect WR performances in fantasy contests.

WR fantasy performances when facing shadow coverage, on average, will finish below 10 PPR points two of each three times he's shadowed, and above 15 PPR points fewer than one of each six games in which he faces shadow coverage. The percentages yielded by the first and second studies are virtually the same, confirming our first findings.

More importantly, and again on average, wide receivers have performed to an average of -3.9 PPR points below their PPG season-average marks against shadow corners this season (it was a bit lower at -4.0 after W7). The impact is quite real.

Splitting the WRs in tiers, though, we get the following results:

• WR1 (17+ PPG this season) have scored -6.5 PPR points per game below their PPG season marks against shadow coverages through W10 (it was -6.6 through W7)
• WR2 (14 to 17 PPG) have scored -6.2 PPR points per game (from -6.2)
• WR3 (10 to 14 PPG) have scored -4.0 PPR points per game (from -5.6)
• Lower-tier WR (0 to 10 PPG) have scored -1.6 PPR points per game (from -1.1)

Looking at raw PPR scores against shadow-coverage matchups:

• WR1 (17+ PPG this season) have scored an average of 12.8 PPR in the games they've been shadowed (from 13.3 through W7)
• WR2 (14 to 17 PPG) have scored 9.7 PPR (from 9.7)
• WR3 (10 to 14 PPG) have scored 6.2 PPR (from 6.2)
• Lower-tier WR (0 to 10 PPG) have scored 5.3 PPR (from 4.9)

The main takeaway is that while "normal" WR/CB matchups don't have much impact on WR performance (-0.12 to +0.12 PPR per target on average), shadow coverage does in fact greatly impact WRs.

As we have seen, shadowed WRs score an average of -3.9 PPR points per game below their season average PPG, and an average of near -0.25 PPR per target below their season average PPR/T.

That being said, though, nobody should sit WR1 D.K. Metcalf because he's facing Stephon Gilmore in redraft leagues (he cooked the matchup to score 19.2 PPR points, 1.9 above his season PPG) in order to start some WR2 or WR3 in a better matchup, as the latter won't probably even reach a good fantasy-baseline even on the sweetest of matchups/coverages.

In the same way, nobody should believe that D.K. Metcalf is going to put up a dud such as he did against Patrick Peterson's shadow in Week 7 (4.3 PPR; -13.0 below his season PPG), as that was most probably an extremely unique outlier.

Those differences in performance can be critical in certain DFS contests, but as far as redraft leagues go, you would end in a much better place in the long run if you always play your studs and believe in their abilities to overcome shadow corners and "bad" matchups.

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