Disguise is an important tool for any defensive coordinator to have in his toolbox. It’s critical, especially at the NFL level, that quarterbacks spend as many plays as possible not trusting what they see pre-snap. This prevents them from getting into the best possible play at the line, slows down their decision-making, and can often lead to turnovers.
“Cover-2 Robber” is a great disguised coverage that’s set up to generate those turnovers. Even the most experienced quarterbacks have difficulty recognizing it.
Chiefs Defensive Coordinator Steve Spagnuolo (Who now has an NFL-record 4 Super Bowl rings as a DC) loves to use this look and was especially effective doing so with Tyrann Mathieu roaming his secondary for 3 seasons.
On this example from 2019, he was even able to fool Philip Rivers, a 16-year veteran at the time. This was 3rd-and-8. The Chiefs lined up against the Chargers’ 3×1 set in a 2-deep look with Mathieu as one of the deep safeties:
At the snap, Mathieu stepped up underneath and the other deep safety, Juan Thornhill, rotated towards the middle of the field: