Knowing the head coaches and coordinators goes a long way to understanding what happens and why in the NFL. They're the guys who put it all in motion. The players are just chess pieces, albeit some with greater powers than others. Being aware of coaches' work history, and who they learned from on the way up the coaching ladder, sheds a lot of light on why teams play the way they do, and why certain tendencies develop in both style and substance. Being hip to the ways of coaching staffs also helps to project how teams will play in the near future.
The directory below includes a team link (in bold) to the bios of all coaches on staff -- head coach, coordinators, plus all position and quality control coaches.
Attention NFL handicapping folks: Always check for relevant coaching connections in match-ups.