Blood, sweat, and chalk

"The modern game of football is filled with plays and formations with names like the Counter Trey, the Wildcat, the Zone Blitz and the Cover Two. They have become part of the sport's vernacular, and yet for many fans they remain just names, often confusing ones. To rectify that, Tim Layden has drilled deep into the core of the game to reveal not only how these chalkboard X's and O's really work on the field, but also where they came from and who dreamed them up..."--Dust cover flap.