Variety is the spice of play-calling
In his 1999 autobiography "Think Like a Champion," Mike Shanahan talked about specific multi-receiver sets, featuring running backs in unusual spots, that keyed defensive intent. "It's no accident that the offensive formation we used three seasons ago," he said then, "with our normal offensive personnel lining up in a five-wide receiver set — has shown up around the league. By lining up our wide receivers inside and our running backs outside, we were able to see, before the snap, whether the defense would be in man or zone coverage. The quarterback was able to get a pre-snap read, giving him a distinct advantage. Now, other teams look for that advantage. They have duplicated the formation." This example calls for the lead back to motion into the backfield after the defense's intent is deduced. While Jim Zorn's version of the West Coast offense alternated between staid conservatism and ineffective trickery for its own sake, Shanahan's experience with formation and personnel diversity allows him to bring a more varied palette to the game.
— Doug Farrar