Well the thing is, with a defensive playbook...it's more of schemes as opposed to plays in an offensive playbook. If you're handing out offensive playbooks you can see where people are going to be going on the field...but even still, with a big playbook like most college and professional coaches have now days, looking at a playbook is about as good as looking at film of them playing...unless the playbook is giving out the "calls" or "secret terminology". I hate to bring this up about Saban, but he got caught taping audio of the Patriots, while he was with the Dolphins. The next time they played the Patriots they beat them even though the Patriots were a much better team.
I love looking at defensive schemes like that. I tend to be more defensive minded...kinda like Saban (although we're not on the same level). The standard 4-3 defense is fun to look at, but I love looking at different schemes such as Saban's style 3-4...and I find the 3-3 (Rich Rod's and J. Kines) interesting. But I'm not that big of a fan of a full-time 3-man front.