One-platoon system

The one-platoon system, also known as iron man football, was a system in American football where players played on both offense and defense. It was the result of rules that limited player substitutions, rules that are also standard procedure in many other sports, but were eliminated in the 1940s. The alternative system is known as the "two-platoon system", or simply the "platoon system", because of its use of separate offensive and defensive units. Each system was used at different times in American college football and in the National Football League.

History
Prior to 1941, virtually all football players saw action on "both sides of the ball," playing in both offensive and defensive roles. From 1941 to 1952, the National Collegiate Athletic Association (NCAA) allowed unlimited substitution. This change was originally made because of the difficulty in fielding highly skilled players during the years of the Second World War, in which many able-bodied college-age men volunteered for or were drafted into military service.

The first known use of the so-called "two-platoon" system was by Michigan head coach Fritz Crisler in 1945. Crisler utilized eight players each who played only on offense and defense, with three playing both against an Army team under head coach "Colonel" Earl "Red" Blaik. Michigan lost the game 28–7, but the system impressed Blaik enough for him to adopt it for his own team. Blaik, a former soldier himself, coined the "platoon" terminology in reference to the type of military unit. Between 1946 and 1950, Blaik's two-platoon teams twice finished the season ranked second in the Associated Press polls and never finished lower than 11th.

In 1954, the NCAA emplaced a set of new rules requiring the use of the one-platoon system, primarily due to financial reasons. The system allowed only one player to be substituted between plays, which effectively put an end to the use of separate specialized units. Tennessee head coach "General" Robert Neyland praised the change as the end of "chickenshit football".

After the 1964 season, twelve years since the mandate requiring one-platoon, the NCAA repealed the rules enforcing its use and allowed an unlimited amount of player substitutions. This allowed, starting with the 1965 season, teams to form separate offensive and defensive units as well as "special teams" which would be employed in kicking situations. The reinstatement of the two-platoon system allowed players to become more specialized by focusing on a limited number of plays and skills related to their specific position. By the early 1970s, however, some university administrators, coaches and others were calling for a return to the days of one-platoon football.

The sport of arena football used a limited one platoon system (from which quarterbacks and kickers were exempt) from its inception until 2007.

Controversy
The 1954 rule change and its subsequent reversal were not without controversy. Numerous coaches, pundits, and athletic department officials have argued on both sides of the debate.

Arguments in support of one-platoon football

 * A significant reduction in financial expenditures through reducing the amount of scholarships, equipment, and staff. Kansas State president Jon Wefald estimated that one-platoon football would result in a 40% reduction in expenditure.
 * It would "get back to the basics" by simplifying the playbooks and focusing on the fundamentals. Former Missouri head coach Dan Devine said, "Blocking doesn't teach you to tackle, so what two-platoon football does is make a man a lesser player ... We have these kids who have never blocked and the other half who have never tackled."
 * It would result in better athletes, both by improving players under the system and eliminating "one-dimensional" specialists from the game. Former Washington State head coach Mike Price said that the "all-around athlete would become a star again. He would play all the time."
 * A potential reduction in the risk of and severity of injuries by creating more equal match-ups between players.
 * A potential reduction in the severity of injuries by reducing the speed of the game and thereby the force of collisions.
 * A limitation on the role of coaches and increase the role of player decision-making. College athletics were originally formed as a diversion for student athletes and should therefore maintain a focus on the players themselves. Oklahoma head coach Bud Wilkinson said two platoons caused an increase in the size of the coaching staff, and a decrease in the importance of the head coach himself.
 * It would potentially make smaller schools more competitive with the "big-time" college football programs by decreasing the roster size and thus deepening the pool of available prospects to each team.
 * The use of specialized football players is not in keeping with the "true" nature of the game (cf. the argument against the designated hitter rule in baseball).
 * Football scholarships are a privilege, not a right. Former Iowa State head coach Jim Walden said, "Nobody promised we'd have trees to cut down forever or that people would burn coal forever or that we'd have 95 scholarships forever."

Arguments in support of two-platoon football

 * It allows a more diverse assortment of players. Individuals with different physical builds and body types can be competitive in specialized positions, whereas they would not be if required to play in both offensive and defensive capacities. In a 1954 issue of Sports Illustrated, then-Michigan State athletic director Clarence Munn stated that, "One-platoon rules have forced a return to the big man, the 220-pound lineman who can withstand the pounding of two-way football."
 * An increase in the speed, and thereby the excitement, of the game.
 * An increase in the complexity and intellectual aspect of the game.
 * A potential reduction in the risk of injury to due to less fatigued players, and because players would spend less time on the field.
 * A decrease in the role of coaches by eliminating a "substitution battle of wits" and potential gaming of substitution rules.
 * It allows more college athletes to acquire scholarships to attend universities for which they might otherwise not be able to compete.
 * It would allegedly help smaller schools, due to big-time college football programs maintaining a monopoly over potential two-way recruits.
 * Modern defenses such as the 4-3 defense and 3-4 defense did not exist at the time when one-platoon football was mandated. As a result, a return to one-platoon football would cause hardships due to the fact that the offense is still mandated to have at least five ineligible receivers while the defenses would not be subject to such restrictions. This would result in the need for a trade-off: either build the team for offense and go back to older, less effective defenses such as the 5-2 defense, or build the team for a modern defense and put undersized linebackers on the offensive line. Either option compromises quality of play on either side of the ball.

Noteworthy professional one-platoon players

 * Sammy Baugh – Washington Redskins quarterback, tailback, defensive back, and punter credited with revolutionizing the use of the forward pass. Baugh was the 1943 NFL leader in passing, interceptions, and punting.
 * Chuck Bednarik – Pennsylvania and Philadelphia Eagles linebacker and center, first-overall 1949 NFL Draft selection, and professional football's last full-time two-way player. Bednarik has been an outspoken critic of the modern football player's lack of stamina under the two-platoon system.
 * Charley Trippi – Georgia college and Chicago Cardinals professional quarterback, halfback, punter, and return specialist, also switched to defence and remained punter for his final (1954, 1955) seasons with the Cardinals. Jim Thorpe called Trippi "the greatest football player I ever saw."
 * Troy Brown – New England Patriots wide receiver who made 17 receptions in their 2004 season, also contributed in what was originally an emergency role on defense as a cornerback, ranking second on the team in interceptions with three.
 * Mike Furrey – After playing one-platoon football in the Arena Football League in 2002 and 2003, Furrey played on both sides of the ball with the NFL's St. Louis Rams, Detroit Lions, and the Cleveland Browns at wide receiver and safety. Furrey did not see defensive game action in a season in which he also started on offense. He has recorded 10 career pass deflections and four career interceptions on defense, and 221 career receptions and seven career touchdowns on offense.
 * Julian Edelman – After playing quarterback in college at Kent State, Edelman switched to slot receiver and kick returner after being drafted in the 7th round. Due to injuries to the New England Patriots' secondary in the 2011 NFL season he was utilized as a slot cornerback on defense and is seen as the new Troy Brown for the Patriots because of his versatility.