The flexbone formation is an offensive formation in American football that uses a quarterback, five offensive linemen, three running backs, and varying numbers of tight ends and wide receivers. The flexbone formation is a predominant running formation derived from the wishbone formation and it features a quarterback under center with a fullback lined up directly behind the quarterback. There are two smaller running backs called slotbacks aligned behind the line of scrimmage on each side of the offensive line. The slotbacks are sometimes incorrectly referred to as wingbacks. But, in order to be a wingback, there must be a guard, tackle and tight end all on one side of the center on the line of scrimmage and then the wingback off the line of scrimmage (as featured in the unbalanced formation diagram).
Air Force Academy Head Coach Fisher DeBerry was once quoted as saying "we need to be more flexible in the Bone." Hence, the term "Flexbone" was born. The design of the formation itself, however, was not created by Fisher DeBerry. The flexbone is a literal carbon copy of the Double Slot formation that Glenn "Tiger" Ellison had created over two decades before the flexbone was born. Incidentally, the option-style running game in the flexbone is based entirely around the Cowboy and Gangster series' of Ellison's Run-and-Shoot playbook.
Triple option 
The basic play run from the flexbone is known as a triple option, or veer. Often the quarterback first sends one of the slotbacks in motion to the other side. While he is still in motion behind the fullback, the quarterback then receives the ball from the center. Next, the fullback (FB) either takes the football from the quarterback or 'fakes' that he has taken the football. If the fullback takes the football, then he runs straight into the line of scrimmage and attempts to gain yardage. If the fullback does not take the football, then the quarterback sprints parallel to the line of scrimmage with a slotback trailing him. The quarterback can either turn upfield or pitch the football to the trailing slotback. Hence the term triple because the fullback is option number one, the quarterback keeping the ball is option number two, and the quarterback pitching to the slotback is option number three. The triple option forces defenses to worry about fullbacks running in the middle of the offensive line and to worry about quarterbacks and slotbacks running to the outside of the line. The decision of who is to carry the ball (which option to make) can either be made before the play in the huddle, or during the play by the QB, who will make decisions based on the position and play of certain defensive players and what they are doing. The quarterback reads the defensive end on the side the play is going to when deciding whether to hand to the fullback or to keep it himself. If he sees the end is committed to stopping the fullback in the middle, the QB will keep it. If the end is staying back to contain the QB on the outside, he will give it to the fullback. If the quarterback does not hand to the FB, he will then read the end to see if he is committed to playing the SB on the pitch or the QB. If he is playing the QB, then he will pitch it to the slotback. If the end is committed to stopping the slotback on the pitch, the QB will take the ball upfield himself.
Arguably, the two most difficult positions on offense to develop quickly are wide receivers and quarterbacks. A style of play was needed for teams that could not field strong throwing quarterbacks. In the flexbone formation, intelligent and athletic personnel can adapt to playing a quarterback's position without having to throw the ball very well. Flexbone teams are often playing against more talented teams so they must use time management and trickery of the flexbone to even the playing field. By running the ball almost exclusively, a flexbone offense also runs the game clock and limits the opposing teams possibly faster and stronger offense from scoring against their own defense.
Another key consideration is that the flexbone formation gives the offense four potential vertical receiving threats at the snap: the two wide receivers and the two slotbacks. This is something that alternative formations such as the I-formation or the traditional wishbone cannot achieve without pre-snap motion that tips the offense's hand. This advantage allows the four-verticals play, a deadly weapon against Cover 3, a common defensive coverage used by the eight-man fronts that a strong running team is likely to face.
Since this offense is primarily used by service academies (Air Force, Army, Navy, The Citadel), it helps alleviate the inherent unbalance related to recruiting and being unable to recruit the type of talent that a larger school like Oklahoma or Alabama might be able to. The Flexbone allows for QBs who may be shorter or smaller than ideal (5'10 - 6'2 and weighing around 185-205 pounds) to be able to start because they often have a speed advantage despite not being able to throw the ball as well.
As a result of the misdirection and the size of the outside WRs (usually 6'2 or taller and over 200 pounds) to help block, the slotbacks can be similarly sized to the QB. This allows for the Flexbone to have 3 players who can run fast (with SBs also helping serve as receivers or lead blockers) while the FB can be a more traditional HB size of 220-235 pounds.
Requirements to succeed 
- The offense needs an intelligent and fast quarterback who isn't afraid to take a hit, a strong fullback, and two quick slotbacks. The quarterback must be able to read a run defense in order to exploit the holes. His read will determine how to develop an option play. Good flexbone quarterbacks are capable of manipulating overpursuing defenses.
- The fullback must be strong enough to break tackles and draw the attention of linebackers and defensive linemen. Good flexbone fullbacks are usually the best ball carriers on the team and receive the majority of rushing attempts. A flexbone fullback is usually smaller and faster than a typical fullback seen in conventional offenses.
- The slotbacks must be balanced athletically, capable of trailing the quarterback, and good receivers. If the slotbacks are not of equal talent, then a defense can predict which direction the play will develop. Slotbacks typically need to be capable pass receivers because they receive a great deal of high velocity pitches and are primary receivers during passing plays.
- The offensive line is smaller and lighter than offensive lines in traditional offenses. This is because linemen must be quick enough to get to linebackers and safeties. They also need to be strong enough to block the defensive line, although teams usually utilize double and combo blocking schemes to overcome the disadvantage in size.
- Wide receivers must be avid open field blockers. They are usually asked to block cornerbacks who are generally the fastest and quickest players on the opponent's defense. Wide receivers aren't at the highest priority in flexbone team's recruitment since they aren't after the greatest wide-outs in the market. However, flexbone receivers do need sure hands. As a run-heavy offense, flexbone can create a great deal of havoc amongst defenses if - alongside with strong run game - they can establish even a simplest of passing attack with sure-handed receivers.
Use of the flexbone formation 
In Division I Championship Subdivision football, Georgia Southern pioneered a version of the flexbone that won a record six NCAA Championship Subdivision National Titles and nine Southern Conference titles. Through the 2007 season, the United States Air Force Academy and the United States Naval Academy were the last major remnants of flexbone football in division I-A and testaments to the formation's ability to use key offensive players effectively when a team has significantly less talent on the field. But with the hiring of former Navy head coach Paul Johnson in 2008 and who also coached at Georgia Southern, Georgia Tech became the first BCS conference school in approximately two decades to use a flexbone offense. In Johnson's first year at Georgia Tech, the Yellow Jackets shared the ACC Coastal Division title with Virginia Tech. In 2009, the Jackets beat Clemson in the ACC Championship game to get to the FedEx Orange Bowl. In the late 1980s, the University of Arkansas ran a version of the flexbone under coach Ken Hatfield and won two consecutive Southwest Conference titles.
On the highschool level, many teams across the country have opted to use the flexbone. One successful switch can be seen in Hutchinson Kansas, as the Hutchinson High Football team has become a top tier team in the region having won 7 state football championships (4 in class 6A and 3 in class 5A).
Famous Flexbone players 
- Fullback - Kyle Eckel (National Football League)
- Quarterback - Tracy Ham (Canadian Football League, Georgia Southern)
- Quarterback - Jaybo Shaw (Georgia Southern)
- Quarterback - Jerick McKinnon (Georgia Southern)
- Quarterback - Dee Dowis (Air Force)
- Quarterback - Scotty Jirtle (Air Force)
- Quarterback - Quinn Grovey (Arkansas)
- Quarterback - Shaun Carney (Air Force)
- Quarterback - Mark Harmon (UCLA), more well known as an actor
- Slotback - James Rouse (Arkansas), (NFL)
- Fullback - Barry Foster (Arkansas), (NFL)
- Fullback - Jonathan Dwyer (Georgia Tech), (NFL)
- Slotback, Fullback - Anthony Allen (Georgia Tech), (NFL)
- Quarterback - Joshua Nesbitt (Georgia Tech)
- Quarterback - Ricky Dobbs (Navy)
- Fullback - Adrian N. Peterson (Georgia Southern)
Famous Flexbone coaches 
- Fisher DeBerry - Air Force
- Paul Johnson - Georgia Southern, Navy, Georgia Tech
- Erk Russell - Georgia Southern
- Jeff Monken - Georgia Southern
- Mike Ayers - Wofford
- Ken Niumatalolo - Navy
- Ken Hatfield - Air Force, Arkansas, Clemson, Rice
- Janak, Vance. "Hutch High wins State again". -. The Hutchinson News. Retrieved 06/03/2011.