Walking off the field Sunday after his heavily favored New England Patriots lost to the Buffalo Bills, Bill Belichick may have been thinking, By Jove, I've created a monster.

In the copycat NFL, where no effective piece of game-planning goes unnoticed for more than 14 seconds, Buffalo may have won the early prize for the innovation of the year—one that is playing a leading role in the team's surprising early-season breakout. You can call it the "stack," the "bunch," or maybe even the "spread scrunch."

Belichick's...