Receivers read the defense on the fly. This is probably the biggest difference between the modern "spread" and the 'shoot. Some of that distinction is a matter of shades of gray, but in other cases it is quite dramatic. The point about formations was made above, but the basic theory behind the offense goes back to the originator, Tiger Ellison. As the story goes, he wanted an offense that emulated what was most natural, so he observed playground and backyard football. He said you didn't see highly formalized lines and alignments or wedge plays and all that. Instead you saw a kid, on the run, tossing passes to receivers who would keep moving until they found open spots. To Ellison, if you didn't coach the kids too much they began "run and shooting" on their own, so he thought this was how people really want to play. Hence, his receivers would read and react on the fly to get open.
http://smartfootball.blogspot.com/2009/ ... art-1.html
