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:


 * Who decides which play to run? In some systems, the decision for choosing the play is made by a coach on the sidelines.  Depending on the team, this can be either the head coach, or an assistant known as the offensive coordinator.  In other systems, the decision is made by the quarterback on the field, with little direct input from the coaches on each play.


 * How is the play relayed to the players on the field? In most systems, some form of a huddle is used to gather the players together.  In the huddle, the quarterback is usually the player tasked with relaying the play (whether called by a coach on the sidelines or himself) to the other players.  The quarterback himself gets the plays in a variety of ways: he may have a speaker in his helmet where a coach directly tells him which play to call.  A player can be sent in from the sidelines as a substitute on each play, and he can tell the quarterback the called play.  The play can also be communicated from the sidelines via hand signals or pictures.  Increasingly, teams are also employing a form of offense called the no-huddle offense to speed the game up.  In such systems, instead of meeting together in a huddle, the players assume their positions as quickly as possible, and get their assignments from their position rather than the huddle.  In such cases, the players may receive their assignments from the quarterback or from the sideline directly.


 * What language is used to describe the plays? Language is the key distinction between play calling systems.  Each play a team runs is usually assigned a name.  Players are often expected to learn a team's entire playbook, and as the number of plays can often number in the hundreds, the language used to name each play can be an important mnemonic in a player understanding what his role in that play is.  Depending on the system, plays may be identified by a complex language of numbers, letters, and other words that clearly explain what the role of each player is.  For example, in one particular system a play may be called "896 H-Shallow F-Curl".  The "896" refers to the routes that the three receivers (the split end, the tight end, and the flanker), are to run, with each digit referring to a specific route, while the "H-Shallow" and "F-Curl" refer to routes run by the halfback and fullback respectively.  In other systems, instead of telling each individual player what they are supposed to do, an entire package of routes may be indicated by a single word like "Ghost" or "Tosser".  The specific language used to communicate a play is not a trivial matter as complicated names make quick communication in the heat of a game difficult, while shorter, simpler names often require players to have more of the playbook memorized, which itself is not an easy task, coaches often have to strike a balance between having a system where the name of a play contains enough information so each player knows what do to, but the longer the name of the play the greater the opportunity for miscommunication and misunderstanding.

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:


 * Red Right 30 Pull Trap: "Red Right" refers to a specific formation, in this case the pro set formation with three receivers and two backs. The receivers include a split end to the left, a tight end and flanker to the right, while the backs consist of a halfback and a fullback behind and two yards behind the quarterback.  The fullback is lined up on the strong side (the side of the formation with the tight end) behind the right tackle, while the halfback is lined up behind the left tackle.  "30" refers both to the "series" of plays (3X plays are all toss plays, where the quarterback delivers the ball to the half back with an underhanded toss) and the "hole" the running back aims for in his run (X0 plays mean the running back heads for the "0-hole", which is the gap between the center and right guard).  "Pull trap" describes the blocking system: in this case the backside guard (the one away from the flow of the play) will "pull" out from his normal position to "trap block", which means he leads the running back through the hole and blocks the linebacker back towards the backside of the play.


 * FB West Right Slot 372 Y Stick: "FB West Right Slot" is the formation. FB indicates that the fullback is playing out of his normal position.  West Right indicates that the fullback would line up immediately to the right of, and one step back from, the tight end, who is lined up on the right.  Slot indicates that the flanker, who usually plays on the same side as the tight end, but split wide, is instead lined up on the left, in the "slot" between the split end and left tackle.  372 tells the series of plays: 3XX indicates that the quarterback will make a shorter, three-step drop rather than the standard five-step drop.  X7X is the specific series of passing plays, all based around using the halfback to block on the weak side (away from the tight end).  XX2 indicates the specific blocking scheme, telling each of the blockers what their blocking assignment is.  "Y Stick" describes the pass route to be run: the "Y" receiver (the tight end) will be the primary receiver and run a stick route: he will run forward, fading slightly towards the center of the field for six yards, and then he'll suddenly change course, breaking straight for the right sideline.

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:


 * 1) flat: At the snap, the receiver runs towards the sideline closest to him, aiming for the point where the line of scrimmage meets the sideline.
 * 2) slant: At the snap, the receiver runs at a 45° angle towards the center of the field.
 * 3) comeback or hitch: At the snap, the receiver runs down the field, then stops quickly and turns his body towards the sideline.
 * 4) curl or buttonhook: At the snap, the receiver runs down the field, then stops quickly and turns his body towards the middle of the field.
 * 5) out or jet: At the snap, the receiver runs down the field, and at a set point turns to run straight at the sideline, parallel to the line of scrimmage.
 * 6) dig or drag or in: At the snap, the receiver runs down the field, and at a set point turns to run straight towards the center of the field, parallel to the line of scrimage
 * 7) corner or flag: At the snap, the receiver runs down the field, and at a set point turns to run towards the sideline at a 45° angle.
 * 8) post: At the snap, the receiver runs down the field, and at a set point turns to run towards the middle of the field at a 45° angle.
 * 9) Fly or go or streak: At the snap, the receiver runs straight down the field as far as he can, parallel to the sideline.

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.