I Love Rex Ryan.
It's true. The man is crazy like a fox, aggressive as hell, and brash like you read about. At least part of this is because of the fictional character Rex Ryan from NFL humor blog KissingSuzyKolber, which I think may not actually be all that fictional. Ex: Careful, naughty, hysterical language compared with Real Life Naughty Language. I ask you, WHICH ONE IS THE REAL REX???
Humor aside, Rex Ryan is a phenomenal coach who just does things differently. I've seen diagrams of some of his blitz schemes that he's actually run with the Jets and they are both BRILLIANT and INSANE. Probably the most ridiculous example would be a blitz where he rushes three on two to the blitz side and then has a 1 tech loop to outside contain on the other side, all while playing standard cover 3 behind it. The quarterback gets the perception of pressure, but the defense gets the security of full, uncompromised coverage, so it's really a win-win for the D.
I Really Like The 46.
I think that it behooves just about any defense to have a 46 front change of pace. My D of choice is a 3-4, which I think matches up brilliantly with the 46, but I know 4-4, 4-3, 3-3 coaches who all have 46 packages in their playbook. The 46 lets you cover up your LBs, puts immediate and central pressure on the OL and QB in passing game, and, all things considered, is relatively cheap to install. If you run man coverage and shade your DL, you can do it. If you don't, you still can because the DL's assignments are very simple and you can run some pretty simple 3x3 zone out of it.
On With The Book
This book is thorough and easy to understand while presenting the ins and outs of the entire scheme. It's like getting a simplified version of the DVD set for much cheaper. You come away with a great understanding of how to install, adjust, and coordinate the 46 in a way that follows Ryan's acronym K.I.L.L.: "Keep It Learnable and Likeable". There's two sections that are great and fairly scheme independent: the first on loaded zone coverage and the other on 3 technique play. Both can be easily translated to other defenses quite easily.