When the San Francisco 49ers defense was at its best under Robert Saleh, it was built around a four-man rush that was talented enough to create an elite level of pressure without the assistance of a blitz. This allowed Saleh more chess pieces at his disposal in the secondary. In their 2019 Super Bowl season, the 49ers ranked second in pressure rate (28.7%) and third in sack rate (8.5%), despite blitzing at the fourth-lowest frequency (20.9%). That is the perfect formula for cooking up a top-tier defense.
The New York Jets have not been able to play defense this way for the longest time.