This. /\
One thing to not forget, is there is a certain amount of homage paid to the sanctity of the historic cadence barked by the NFL quarterback. A portion of it speaks to alignments, and another to adjustments, with a final bit to lock the o-line into the "set" before the snap, but without the QB cadence it's just not football, IMO, and many QB's have fun with it.
The interesting thing I have noticed, is that a variety of teams use "Green 80!", not just the Seahawks, same holds true with "Omaha!". The "Blue 18" is just the latest wrinkle. It's just the latest and greatest way to say what has always been said.
My favorite cadences came from guys like Elway and Dan Fouts, but nothing beats Boomer Esiason calling-out Sam Wyche's "Bengal Terminology" at the line in the 80's. They didn't use a contemporary cadence because they ran a no-huddle. They simply coded the plays and called them out loud from a handful of sets that Boomer would yell out initially. Once everyone was located, he would call the play and either check out or run it depending on the defense he saw.
For example: "28 Baker Bruce" meant a play-action pass to the #8 receiver, running his #2 route, with the tailback blocking the strong safety. "Baker" was the play action call and "A" sound indicated the side/direction, "Bruce" is the "Boss" which meant Back On Strong Safety. Each player new ahead of time what the routes and assignments were, so if they didn't hear their number called, they would block/run-routes according to the last two or three words of the call. It was cool, until defenses eventually figured it all out.
Today, it's more about blocking assignments than anything else, as most of the pre-snap chatter involves who blocks who in the ZBS, and that all starts with who is the MLB.
