Scout.com: Chalk Talk: West Coast Offense Part I
"Most NFL fans associate the West Coast Offense with Bill Walsh’s 49ers teams of the 1980s. But the seeds of Walsh’s system in San Francisco were planted 20 years earlier by Gillman and in a much different form. Any team that presently runs an offense that is predicated on short timing patterns is tagged with the West Coast label. But unlike Walsh, Gillman had no use for short passes. His philosophy involved a more vertical attack, similar to Mike Martz’s 'Greatest Show on Turf' offense while with the St. Louis Rams.
It was during Gillman’s days with the Chargers that San Diego State head football coach Don Coryell began frequenting the Bolts’ preseason camps with his two young assistant coaches, Joe Gibbs and Ernie Zampese. They loved what they saw of the offense and began developing it further for their Aztec teams. Coryell began adding his own innovations and building on what Gillman had started. By the time Coryell took the head coaching position for the Chargers in 1978, his scheme had become known as ‘Air Coryell.’ In nine years with the Chargers, Coryell’s offense led the NFL in passing yardage seven times.
Joe Gibbs then took the offense with him to the Washington Redskins in 1981. His tinkering with the system involved adding the bunch formation – three wide receivers lined up together, each darting off in confusing patterns – and the two- and three-tight end alignments, resulting in three Super Bowl championships."
(Here's Part II of the article:
Scout.com: Chalk Talk: West Coast Offense Part II)