The level of aggressiveness is limited by the scheme. Year in and year out, history proves it to be the lowest blitz percentage defense. Most likely around 10%, and no more than 15%. Every scheme has it's limitations in what it can do and what it can do successfully. Blitzing too much out of this scheme leaves many vulnerabilities in favor of the short passing game which is obviously the prevalent choice of attack for the majority of today's offenses. When Burke says we'll go away from the zone blitz, the primary tactics for us to be aggressive besides front 4 pressure are to stunt/twist the d-line, and sugar the A gaps w/ the LBs.
The scheme, especially in combination of the stream line talk, relies on pass coverage execution by the back 7 to cover long enough for the front 4 pressure to get home. Every scheme has it's advantages/disadvantages and strengths/limitations. We're not an aggressive defense by way of blitzing, we're aggressive by allowing the defensive line to hunt the QB. It's how were built by scheme, and player prototype and skillset. It's just how it is.
