I have nothing backwards.
The whole C2/T2 defense is designed to be effective but only if your front 4 can get pressure alone.
Will it give up alot of short passes to recievers? Sure, but it doesn't give up the deep ball and forces offenses to be patient dinking and dunking down the field.
Understanding NFL Football: The Cover 2 Defense - Associated Content from Yahoo! - associatedcontent.com
Lots of other articles out there that you can read that basically say the same thing.
As to our "Sack Leader". Watch when JA gets his sacks. Not many come with just our Front 4 getting the pressure. Almost all of them come when we have atleast 2 LB'rs show a "Mug" look in the A or A and B gaps presnap.
Again, once you start bringing help, you aren't playing the C2 anymore. Your playing either a Cover 3 (Cloud) or a man to man press look. When you start doing that, as you said, our defense can get carved up.
Blame the secondary if you want, but reality is, our scheme won't work without our DL doing its job. Even though we have some sacks, it isn't, for the most part, doing its job.