As an assistant with the Cincinatti Bengals, Bill Walsh developed an offense strategy called the West Coast offense. This system used multiple receiver sets and short, precise passing that countered the traditional football strategies of run-based offenses and downfield passing. Walsh later became head coach of the San Francisco 49ers and won three Super Bowls with this innovative offense. He created one of the most prolific offenses of all time with legendary players such as Joe Montana and Jerry Rice. Because of its enormous success, many other head coaches began to adopt the West Coast offense to try to replicate the success of Walsh’s famous team. The spread of this system illustrates many aspects of network theory, including power laws and the diffusion of innovation.

The small-world phenomenon of football coaches is a well known fact, but the West Coast offense did not spread just from Walsh’s protégés. Many other head coaches with no relation to Walsh adopted the West Coast system, or at least elements of it, including such respected coaches as Brian Billick and Mike Martz. The West Coast offense appealed to many coaches looking for an explosive offense. As more coaches replicated Walsh’s success with system, the offense grew immensely popular among head coaches at all levels, especially in the college game, which it is particularly suited for. Following power law distribution, its popularity became self-reinforcing as coaches copied the offense after observing the success of others with it. Even coaches with players ill-suited for running the West Coast offense adopted it thinking that they too could have the same success as Walsh.

Football is an ideal environment to observe power laws. In the cutthroat business of football, coaches are always looking for an edge on the competition, the next innovative formation or play. There is a lot of pressure on football coaches to succeed; their very job depends on it. So it is not surprising that there is much imitation in the NFL, college football, and even high school football. In fact, the NFL is well known as a copycat league. This trend has been around for decades, ever since Sammy Baugh popularized the forward pass in the 1930s with the Redskins.

http://espn.go.com/nfl/s/westcoast/history.html