The offense uses a specific naming system, with the routes for wide receivers and tight ends receiving three digit numbers, and routes for backs having unique names. For example, a pass play in 3 digit form might be "Split Right 787 check swing, check V". (see Offensive Nomenclature). This provides an efficient way to communicate many different plays with minimal memorization.
Several of Walsh's coordinators went on to successfully implement this system at other teams. George Seifert won two Super Bowls with the 49ers. Mike Shanahan won two Super Bowls with the Denver Broncos. Mike Holmgren won a Super Bowl with the Green Bay Packers and coached in another with the Seattle Seahawks. Holmgren's assistant Jon Gruden went on to win a Super Bowl with the Tampa Bay Buccaneers.
At the college level, LaVell Edwards and Dewey Warren created an offensive system similar to the West Coast Offense at Brigham Young University (BYU) in 1973 This offense culminated in a NCAA Division I-A national football championship for BYU in 1984 and a Heisman Trophy for Ty Detmer in 1990. BYU broke over 100 NCAA records for passing and total offense during Edwards' tenure. Several coaches and players associated with BYU's football program had success with this offense at BYU and elsewhere including: Mike Holmgren, Andy Reid, Brian Billick, Ted Tollner, Doug Scovil, Norm Chow, Jim McMahon, Steve Young, Ty Detmer, and Steve Sarkisian among others. The reason for the success in this version of the offense is that it cuts down on complexity. Norm Chow says offenses have around 12 basic pass plays and 5 basic run plays (with screens)--those plays are run from many formations, with plays tagged for a little versatility, so that the players know the offense by the second day of practice. Former Pittsburgh and Stanford head coach Walt Harris also used a variation of the West Coast Offense during his stint at Pittsburgh.
Bill Walsh's West Coast Offense, however, differs from traditional offense by instead emphasizing a short, horizontal passing attack to help stretch the defense out, thus opening up running lanes. The West Coast Offense as implemented under Walsh features precisely run pass patterns by the receivers that make up about 65% to 80% of the offensive scheme. With the defense stretched out, the offense is then free to focus the remaining plays on longer throws (more than 14 yards) and mid to long yard rushes.
Beyond the basic principle of passing to set up the run, there are few rules that govern Walsh's West Coast Offense. Originally the offense used two split backs, giving it an uneven alignment in which five players aligned to one side of the ball and four players aligned on the other side (with the quarterback and center directly behind the ball). Although Walsh-influenced teams now commonly use formations with more or fewer than two backs, the offense's unevenness is still reflected in its pass protection philosophy and continues to distinguish it from single back passing offenses. Throughout the years, coaches have added to, adjusted, modified, simplified, and enhanced Bill Walsh's original adaptation of the Paul Brown offense. Formations and plays vary greatly, as does play calling.
Another key part of the Walsh implementation was "pass first, run later." It was Walsh's intention to gain an early lead by passing the ball, then run the ball on a tired defense late in the game, wearing them down further and running down the clock. The San Francisco 49ers under Walsh often executed this very effectively.
Another key element in Walsh's attack was the three step dropback instead of traditional seven step drops or shotgun formations. The three step drop helped the quarterback get the ball out faster resulting in far fewer sacks. "WCO" plays unfold quicker than in traditional offenses and are usually based on timing routes by the receivers. In this offense the receivers also have reads and change their routes based on the coverages presented to them. The quarterback makes three reads and if no opportunity is available after three reads, the QB will then check off to a back or tight end. Five step and even 7 step dropbacks are now implemented in modern day WCO's because defensive speed has increased since the 80's. Some modern WCO's have even used shotgun formations (e.g. Green Bay, Atlanta '04-'06).
The original West Coast Offense of Sid Gillman uses some of the same principles (pass to establish the run, quarterback throws to timed spots), but offensive formations are generally less complicated with more wideouts and motion. The timed spots are often farther downfield than in the Walsh-style offense, and the system requires a greater reliance on traditional pocket passing.
This is in contrast to the previous quarterback requirements of other systems, which were an adept game manager and a strong arm. Thus, for example, many people reasoned that Johnny Unitas, a strong-armed field general would not have fared well in being subservient to the offensive coordinator, and that his long but sometimes wobbly passes would not have worked in the new system. The West Coast offense caused a split still evident today amongst quarterbacks: those who were more adept at the west coast style (Joe Montana, Steve Young, Brett Favre, Matt Hasselbeck) and those more in tune with the old style (Dan Marino, Peyton Manning, Tom Brady, Jim Kelly)
Also, the West Coast offense requires sure-handed receivers comfortable catching in heavy traffic, and the system downplays speedy, larger receivers who are covered easily in short yardage situation. One result has been the longevity of receivers in the West Coast system (such as the notable Jerry Rice) because a decline in speed is not as harmful, when, in "stretch the field" systems, a receiver who loses a step is a major liability. "WCO" systems also rely on agile running backs that catch the ball as often as they run. Roger Craig was a leading receiver for the 49ers for many years and was a 1,000 yard rusher and 1,000 yard receiver in the 1985 season. Finally, receivers must follow precise, complicated routes as opposed to innovation; so subservient, intelligent players are valued more than independent, pure athletes.
Finally, the West Coast offense, with its emphasis on quick reactive skills, can be seen to further develop the running quarterback motif, where extremely fast running quarterbacks (Michael Vick, Jake Plummer, Steve Young, Donovan McNabb, Vince Young) are valued, if they are good passers, because in blitz or short-yardage situations, when the West Coast offense's value is negated, the running quarterback can make up this difference by posing a threat to make the first down himself, paralyzing an aggressive defense.