One-platoon system

In the college game, the major rules switch allowing two platoons came ahead of the 1941 season — a change first emulated by the NFL in 1943.

One-platoon football is seen currently mostly on lower-end and smaller teams at the high school and semi-pro levels, where player shortages and talent disparities necessitate it.

[4] Substitutions under this "one-platoon system" were thus made individually and strategically based upon time on the clock, field position, and player exhaustion.

[6] Blaik, a former soldier himself, was the one who began using the word "platoon" for this football substitution strategy, in reference to the type of military unit.

With respect to the National Football League, changes in substitution rules were initially driven by the realities of World War II.

Free substitution — apparently intended to help lesser players by allowing longer rest breaks — was implemented in a rule change made April 7, 1943, "for the duration" of the war effort.

[8] A move back to unlimited free substitution was made for another one year trial in the 1949 NFL season, but once again this was paired with a reduction rather than an increase in roster size, this time from 35 down to 32.

[8] Unlimited free substitution was adopted on a permanent basis on January 23, 1950, with rosters gradually growing from 32 to 36 players ahead of the 1959 NFL season.

Starting with the 1953 season, the NCAA emplaced a set of new rules requiring the use of a one-platoon system, primarily for financial reasons.