MANReceiver-based
Follow the assignment
The cornerback has a clear assignment to a single receiver and follows that receiver through the play, often turning their back to the quarterback to stay in coverage.
The charting framework
HOW WE GRADE COVERAGE.
Sticky Coverage evaluates cornerbacks one coverage rep at a time. The emphasis is on the defender's assignment, positioning, and opportunities allowed — not simply whether a pass was caught.
Film-based evaluationsMan and zone graded separately1–3 coverage scale
01
What enters the dataset
Coverage snap selection
A charted coverage snap generally requires the receiver to have a meaningful opportunity to run their route. Not every defensive snap is a coverage rep.
Core inclusion rule
A real coverage opportunity
The receiver must be able to run a route, giving the cornerback an opportunity to execute the assignment and be evaluated.
Coverage reps are a selected subset of eligible snaps, not a count of every defensive play.
Common exclusions and judgment calls
- Screen passes are not charted as coverage reps.
- Zone snaps without receiving threats on the cornerback's side are usually excluded.
- If the QB never looks toward the cornerback and the assignment does not finish the route or visibly gives up, the snap is excluded.
- Hail Mary attempts are ignored.
- Quick first-read throws are usually excluded when the quarterback releases the ball quickly on the first read, unless the cornerback is targeted.
02
Observed responsibility
Classifying coverage
Man and zone describe what the cornerback is doing on the rep, rather than claiming to identify the exact defensive play call.
ZONEArea-based
Protect a region
The cornerback drops into and protects an area of the field rather than chasing one receiver outside that area. A single receiver assignment may not be clear.
This behavior-first approach is especially relevant to pattern-match and hybrid coverages: the charted label reflects the cornerback's practical responsibility on that snap.
03
The evaluation rubric
Coverage grades: 1 to 3
Lower scores indicate a poor rep; higher scores indicate stronger coverage. Man and zone have different descriptions because their defensive responsibilities differ.
Man coverage
01Grade
Failure
A credible completion window opens
The cornerback is beaten by the receiver, who reaches a position where a completion can reasonably be expected. Whether the pass is actually completed does not determine the grade. Game situation, time to throw, and play design are considered.
02Grade
Success
The receiver does not create a good look
The receiver runs most or all of the route but does not reach a position where a completion can reasonably be expected. An exceptional throw or catch does not, by itself, turn a successful coverage rep into a failure.
03Grade
Shutdown
The route is blanketed throughout
The receiver runs the entire route, but the cornerback maintains positioning that makes a completion next to impossible throughout the rep.
Zone coverage
01Grade
Poor
A zone responsibility breaks down
The cornerback leaves their zone open long enough for a reasonable completion opportunity, or is beaten by a receiver entering that zone.
02Grade
Good
The assigned space is protected
The cornerback carries out their zone assignment and prevents the offense from getting a good look in that area.
03Grade
Great
An especially demanding rep is handled
This grade is contextual: for example, several receivers threaten the cornerback's zone and they successfully protect it, or the cornerback decisively shuts down a receiver entering that zone.
Key principle: a catch is not automatically a failed coverage rep, and an incompletion is not automatically a successful one. The grade is based on positioning and the quality of the completion opportunity in context.
04
Alignment
Pre-snap depth
Three categories describe how far off the line of scrimmage the cornerback aligns before the snap.
1Depth code
Press
Near the line of scrimmage
2Depth code
Off coverage
3–7 yards off
3Depth code
Deep off
8+ yards off
Average pre-snap depth is the mean of codes 1, 2, and 3, not a measurement of average distance in yards.
05
The route dictionary
Route codes
The dataset stores routes as numeric codes. These labels describe the receiver's route, except where a zone responsibility is coded instead.
00Hitch
01Flat
02Slant
03Comeback
04Curl
05Out
06In / Dig
07Corner
08Post
09Go / Fly
10Broken play
Zone-specific coding
When no single receiver is clearly being covered in zone, the route value can describe the cornerback's responsibility rather than a literal receiver route:
1 = Flat4 = Intermediate9 = Deep
06
Assignment attribution
Who counts as the matchup?
A matchup is a charting label for the receiver associated with the rep; it is not always a strict one-on-one assignment.
Man coverage
The matchup is typically the receiver whom the cornerback covers for the majority of the snap.
Zone coverage
The matchup is generally the receiver aligned across from the cornerback, or a receiver who makes a catch in the cornerback's zone. The recorded route may be that receiver's route — if it enters the zone — or the area the cornerback is protecting.
07
Reading the leaderboard
How the statistics are calculated
Comparison metrics are calculated from charted rows. The eligible-snap metrics come from a separate weekly input.
Coverage reps
Number of charted snaps in the selected sample. This count responds to play filters.
Average coverage grade
Arithmetic mean of recorded Result values (1–3) across graded reps. Higher is better. It is a charting score, not a completion or success percentage.
Man % / Zone %
Share of the filtered coverage reps categorized as Man or Zone based on observed cornerback behavior.
Average pre-snap depth
Arithmetic mean of depth category codes: 1 = press, 2 = off, 3 = deep off. Not average depth in yards.
Targets, catches and yards
Totals attributed to the cornerback on charted reps. A target or catch does not determine the coverage grade on its own.
Eligible snaps
Separately recorded eligible-snap totals for the games included in the charting dataset. These totals do not change when play filters are applied.
Coverage Rep Rate
All unfiltered charted coverage reps divided by eligible snaps for the same recorded games. This rate also remains static when play filters change.
Coverage grades and matchup attribution involve film-based judgment. These are independently charted evaluations, not official NFL statistics or verified defensive play calls.