Play calling system A play calling system in American football is the specific language and methods used to call plays . Over the years , numerous different systems have existed to communicate , between coaches and players , exactly what the players are supposed to do on any given play . Such systems of play calling are distinguished from " philosophies " of play calling , which are primarily concerned with how the overall strategy of the game is managed , for example if a team is primarily concerned with running or passing , if a team plays fast or slow , what sorts of passes it throws , etc . Instead , the play calling system is primarily concerned with how plays themselves are actually communicated : how specific plays are named , how players can understand their roles based on the naming of the plays , how such plays are communicated to the players , etc . Overview . A football play is a complex entity : during any one given play each of the eleven players on a team has a different , specific , scripted role to play . Each player needs to be able to perform his role well , but the entire team also needs to work together to make the play successful . There is always a balance to be made between clearly communicating the play to the players , but doing so quickly and efficiently enough to fit within the pace of the game , where a team has approximately 30 seconds or less from the end of one play to the start of the next to prepare . A play calling system takes into account all of the following concepts : Specific systems . While there are countless different play calling systems , and every team has their own unique system , in the National Football League three basic systems of calling plays dominates the league : West Coast system . The West Coast system was designed alongside the West Coast offense , though like any play calling system it isn ' t confined to a specific offensive philosophy . Historically , the West Coast system has its roots in the system devised by Paul Brown as the head coach of the Cleveland Browns and Cincinnati Bengals , and is used extensively by members of his coaching tree . The Brown system became the West Coast system when it was introduced , to great success , by his protege Bill Walsh during Walsh ' s tenure as head coach of the San Francisco 49ers during their success of the 1980s and 1990s . In the West Coast system , all plays have names to indicate the specific formation they are run from . Additionally , different systems exist to identify running or passing plays . Running plays are named based on the blocking scheme and the path that the primary ball carrier takes during the run , usually indicating which of nine numbered gaps , or holes , in the offensive line he aims for in his run . Passing plays are named so as to indicate what pass route each player is supposed to take . Here are some plays from one specific West Coast playbook , and what the names mean : Coryell system . The Coryell system was devised by Don Coryell , and is based around the concept of the " route tree " , where each of 9 basic passing routes is given a digit from 1 - 9 . The three receivers get their route assignment from a three - digit number , the left most receiver runs the route indicated by the leftmost digit , the middle receiver by the middle digit , and the right receiver by the rightmost digit . The nine basic routes are as follows : An advantage of the Coryell system is that it allows extremely quick and unambiguous communication with each receiver on a passing play , however this disadvantage is in its limited nature : it only works well in three receiver sets , and only has 9 possible pass routes ( ten if an additional route is assigned to the 0 digit ) . If a route needs to be assigned to someone other than the split end , flanker , or tight end ; or if an unnumbered route is called for , the Coryell system has to adopt the same combination of position letters and route names as the West Coast system , reducing the efficiency advantage . Erhardt - Perkins system . The Erhardt - Perkins system was developed by Ron Erhardt and Ray Perkins , two assistant coaches who worked under Chuck Fairbanks for the New England Patriots during the 1970s . The system was later implemented by the New York Giants in 1982 when Perkins was hired as their head coach , and Erhardt as his offensive coordinator . A third coach who followed Perkins and Erhardt from the Patriots to the Giants was defensive assistant Bill Parcells . Perkins would resign before the season ended , to be replaced by Parcells . Parcells , being primarily a defensive coach , retained Ron Erhardt as his offensive coordinator , and allowed Erhadt to continue to use the Perkins - Erhardt offense , along with its unique play calling system . As a result , the system became disseminated through the league by various members of the Parcells coaching tree , and is used to great effectiveness today by former Cleveland Browns and current New England Patriots head coach Bill Belichick . What makes the Erhardt - Perkins system different from other systems such as the West Coast and Coryell systems is its flexibility . While the other systems use their language to carefully designate what each player on the field is doing at any one time , the Erhardt - Perkins system is based on loose " concepts " which can easily be adapted to a wide array of personnel packages and formations . Thus , a play only needs to indicate three pieces of information : the personnel on the field , the formation they assume , and the concept they intend to run . As long as players have the full set of concepts memorized , every player is essentially interchangeable with every other player , as no player is tied to any one specific route or assignment on any one specific play . A typical Erhardt - Perkins concept involves a set of assignments based on a player ' s location on the field at the start of the play . For example , the " ghost " concept is a three - receiver concept : the outside receiver runs a vertical or fly route , the middle receiver runs an 8 - yard out route , and the inside receiver runs a flat route . The ghost concept will work in any personnel package or formation the team is lined up in , so it can be run with a five wide receiver set in a spread formation , or " base personnel " in the I formation where the fullback motions into the slot position , for example . The Erhardt - Perkins system has advantages and disadvantages . The system requires players who are highly flexible in their abilities : the same player may line up as a running back , tight end , or wide receiver on any given play ; not every player has the correct array of skills to play all of those positions effectively . The system also places a much greater responsibility on the player to memorize and learn the entire playbook ; instead of indicating his exact route on a given play , the player must know every route in every concept , and be able to run each route depending on the exact formation at the time of the snap . Players who are highly successful when playing in other play calling systems can often become lost in the complexities of the system . With the correct types of players , however , the advantages of the system become apparent . Since play calling is very condensed , teams can dispense with the huddle and run at a much faster pace , getting more offensive plays in per game and keeping the defense on its heels . The flexibility of the system also puts the offense at an advantage : the offense can run the exact same pass routes or running plays from very different formations , and more easily get favorable match - ups in coverage ; for example , getting a strong and large tight end covered by a smaller cornerback , or having a speedy wide receiver matched up with a slower linebacker .