Let's take a look at one particular defensive tactic which has given the 2015 Chargers fits over the last 2 weeks, and one they'll have to manage if they want to beat Cleveland on Sunday.
According to Tim Layden's Blood, Sweat and Chalk, the Double A Gap blitz was brought into the modern NFL by the late Jim Johnson, Defensive Coordinator for the Philadelphia Eagles from 1999-2008. Here's an excerpt:
The Double A Gap came in 2001, it was Johnson's ultra-aggressive extension of everything he'd been doing. First conjured when Johnson asked himself this question: Instead of a single blitzer on the edge or a single blitzer in the middle, why not load up the middle of the formation?