My cat just turned 10 this year. My fluffy son, the ball of fur called “Boris,” is clingier than ever now that he’s in double-digit years. Don’t get me wrong: I love that he wants my attention and wants to snuggle all day, every day. Still, this feline stalker also constantly finds his way under my feet, nearly tripping and killing me on daily basis. It doesn’t matter where in the house I post up to write or work or eat; he’s there.

That’s exactly the issue top wide receivers face from defensive coordinators who employ “shadow coverage” to guard them. Just ask Arizona Cardinals receiver DeAndre Hopkins how he liked being tangled up with the same guy for almost three-quarters of his routes run across almost three-quarters of the 2019 season. It can get obnoxious, and (worse) typically only the best cornerbacks are deployed to shadow receivers -- meaning the receiving production likely is limited from the norm.

A top-flight shadow corner can be the difference between your fantasy WR1 leading you to a victory or putting up only flex numbers. Due to that, it’s important for us as fantasy managers to know how shadow coverage tends to affect our weekly lineups and which teams utilize it the most.

It’s time to shed a little light on this subject: how does shadow coverage affect wide receivers in fantasy?

Me and My Shadow

To be completely clear, shadow coverage is when the defender moves with the same pass-catcher around the field from play-to-play. They line up across them pre-snap, and that pass-catcher is their assignment on the play. So, if Tre'Davious White follows Davante Adams across the field in motion but then blitzes or drops into a shallow zone while Adams runs deep, White is not in shadow coverage.

Across the 32 NFL teams, there were 171 instances of shadow coverage being used during the 2019 season, per Pro Football Focus (PFF). That means that, on average, there was a little fewer than 11 shadow situations per week, or that each team used a single shadow defender in about 5.3 games last year.

The reason the strategy isn’t more widely utilized is because not all cornerbacks are good enough to work in shadow coverage. To stick with the Buffalo Bills’ defensive backs, that’s why Levi Wallace and Taron Johnson were not moved around the field despite White’s shadow usage in 2019. Wallace and Johnson combined to allow a 66% catch rate, 10.3 yards per completion, and a 20% missed tackle rate. Having them follow a receiver around would only serve to put them further out of their comfort zones and not benefit the team in any meaningful way.

That said, there are some teams that wield shadow coverage liberally. Using PFF’s shadow tracker from 2019, I looked at both the percent of games that a team used a shadow defender and the rate at which their starting cornerbacks shadowed a receiver. The table below shows the five teams that used shadow coverage the most a campaign ago.

Not only did the New England Patriots use shadow coverage in nearly double the games that the team to use it third-most did, they also almost doubled the occurrences. Coach Bill Belichick wasn’t content to send only Stephon Gilmore around the formation with a team’s top receiver; J.C. Jackson and Jonathan Jones did the same.

A somewhat close second place in this metric is Belichick disciple Matt Patricia and his Detroit Lions, who actually used shadow coverage in more opportunities per game than the Patriots did. This is likely partly due to the opportunity safety Tracy Walker presents to match up with top-flight opposing tight ends like Travis Kelce.

Below are the defenders who found themselves used as a shadow six or more times last season.

There were nine teams who did not use shadow coverage last season: Atlanta Falcons, Chicago Bears, Dallas Cowboys, New York Jets, Las Vegas Raiders, Philadelphia Eagles, Pittsburgh Steelers, Seattle Seahawks, and San Francisco 49ers. There is a mix of strong and suspect secondaries in here, but the overarching factor is that most of these teams use mostly zone coverage principles – they tend to not assign corners to specific receivers, but areas of the field.

A Shadow of Himself

Now we know which teams use the most shadow coverage and which defenders are used as shadows. Still, the billion-dollar question remains: how much does shadow coverage matter for fantasy receivers?

Every receiver who was shadowed in 2019 had some percentage of snaps where their defender wasn't covering them in that game, whether it was 50% of the time or 1%. To figure out the effect of shadow coverage, I compared the receiver's production when shadowed to their production in the rest of the game, then extrapolated both sets of data out to a full theoretical 100% of snaps to compare like sample sizes of snaps (albeit theoretically).

One of the starkest examples comes from Eagles wide receiver Alshon Jeffery's Week 1 duel with then-Washington cornerback Josh Norman. Norman shadowed Jeffery for 94% of his plays, limiting him to 4 catches (5 targets) for 44 yards. In the 6% of plays where Jeffery saw a different defender, he drew one target, caught it, and turned it into 5 yards and a score. Extrapolate those numbers out to a full game’s worth of snaps, and you get 8.9 fantasy points when shadowed and 133.9 when not for a difference in fantasy production of -93%.

I mention this situation to make a point because it’s so extreme, but obviously the exercise exists solely to help us see when shadow coverage worked (or failed) dramatically. No player would ever score 100-plus points in a single game, but this helps us compare rates of production under different circumstances on even ground.

In the average of all players facing shadow coverage, those extreme numbers wash out with the rest and look a lot more reasonable. When we average the production of every wide receiver last year to face shadow coverage and extrapolate both shadow and non-shadow coverage splits out to a full game's worth of snaps, this is what we see.

When a receiver faces a shadow cornerback, the numbers above break down to a decrease of about 42% in potential points – that's the difference between a WR1 in a week and a barely startable FLEX.

Now, I want to give the caveat that not every shadow matchup is created equally. Neiko Thorpe is not going to prevent production the same way that Darius Slay does in isolated man-to-man coverage; that’s not how this works.

The above information is simply the average of all shadow games, where the most elite cornerbacks have gotten more chances than, for instance, Nik Needham or Eli Apple.

In addition, teams have gotten smarter about deploying cornerbacks in shadow coverage; they're not just throwing any old defender on a receiver and letting them play. Only elite cornerbacks get consistently used in shadow coverage, which means when our fantasy receivers are facing this kind of defensive scheme with guys who are shadowing week-in and week-out, we should temper our expectations for their fantasy weeks.

The table below shows the production difference for highly used shadow cornerbacks from last season, with their 2020 team and the percent of fantasy points that they limited opposing receivers to. I included only those cornerbacks who were used as shadows in five or more games last season and averaged 66.7% or more of their snaps in those games in shadow coverage.

Tread carefully if you see one of these cornerbacks projected across from your fantasy receivers. Chances are, they'll cause your fantasy lineup to trip and fall on its face.

Takeaways

Some cornerbacks are good enough to shut down and cause problems for even the best receivers. Good performances from wideouts can come in games when shadowed, but the larger trend is that shadow coverage leads to a dip in fantasy production.

Shadow coverage from an elite cornerback should always concern us, but nowadays, if coaches choose to use shadow coverage, it's likely for good a reason. Take note if your wideouts are drawing a shadow corner of any caliber and consider your alternatives.