One factor is how good will the offense be?
If the offense is still anemic.. then you may need a more aggressive defense.
If the offense is prolific, then you have different schools of thoughts on what defense to run.
The front 4 can also help with that decision. Weak Front 4, may need to go aggressive on coverage and blitz package. Strong front 4, maybe go 2 high and mix underneath.
Bottom line, is that people saying that a particular defense will work is ignorant. You can certainly have a preference as to what defense you'd like to see. But you have to take into consideration what you have as well.. on both sides of the ball. IE, people shouldn't mix what they like to see in a defense and say that a Coordinator doesn't know what he's doing because they are running something different.
