From his article:
To understand how I've come to arrive at my conclusions, and where my opinions and strategies come from, I'll share the following:
I've been lucky enough to have cross-trained with a true master of Kali, and with several other high level knife fighters. I've learned a great deal from them, and some of my content on knife survival has definitely been influenced by this training.
While this has proved invaluable, the bulk of my material is as a result of real world application or observation, mostly from my work experience. I am also part of a larger group which analyses any use of force by law enforcement agencies. I am privy to the nature of violence towards police and the public and measure and evaluate the effectiveness of the response to it. As such, I am involved in the ongoing process of developing training methods and methodologies to respond to the realities of policing in major urban centers. The remainder of my opinions stem from ongoing research - from books, blogs, training, experimentation, interviews and seminars.
Check out his entire series at Japanese Jiu Jitsu: A Journey