Do you have the next six or ten hours free? Settle in and watch Alex Gibbs explain Zone Blocking, and major kudos to the first person that actually does this. I plan on it at some point very soon, because this is a literal goldmine of football nerd information. For those who may not know, Gibbs is best known for developing the modern zone blocking scheme, made most famous out in Denver with the Broncos when they won their two Super Bowls in the late 90's. Gibbs moved on to the Falcons, where he mentored Seahawks Assistant Head Coach Tom Cable, then on to Houston and for a brief while in Seattle before retiring.
Gibbs and Carroll became acquainted when Carroll invited the Zone Blocking Guru to consult for USC back in 2002. "After Pete's first year at USC he was not happy with the direction of his offense," Gibbs said prior to the start of the 2010 season, "He liked what we were doing at Denver when I was a part-time coach there. So I helped him after his first year at USC. I helped coach the coaches at USC. We coached off of film, not the field. I didn't work with any players."
The Seahawks run an iteration of the Alex Gibbs ZBS so if you want to understand the nuances and finer coaching points of Seattle's run game, this will help.