Reader Mark S. asks about the etymology of the term "wild card" as it relates to professional sports and the playoffs.
In American professional sports, when a team enters playoff play without having won their division, they earn what is called a "wild card" spot. It's undoubtedly a snappy term, but why did we start saying it for baseball, football, and the like?
In 1970, after the merger that brought the AFL into the fold, the NFL became the first league to have designated wild card playoff spots. MLB didn't open up their playoff format to involve wild card teams until 1995, so the use of the term in baseball stems from football.
In that first post-merger NFL season, the press referred to the playoff teams we'd currently call "wild cards" with clunky monikers like "the second-place team in each conference with the best winning percentage." "Wild card" was already a football term at the time, but it wouldn't be used in the playoff context until the following season.
"Wild card" originally (and somewhat obviously) comes from poker, which, depending who you ask, started featuring wild cards in the late 19th century. In sports, "wild card" entered the lexicon in the 1960s with college football. It was used to describe a type of substitution that was experimented with throughout the '60s. Here's an early example of its use from 1960 when coaches voted on a new rule (that was later tinkered with and refined):
The college football rules-makers today voted coaches unrestricted use of the “wild-card” substitute for 1960…Under the rules in effect last season, substitutes in groups of two to eleven could be sent into a game twice during a quarter while the clock was stopped. A single player, referred to as a “wild card,” could be substituted only during a time-out and provided he had not used up his two charged entires in the quarter…’A wild-card player now can be substituted at any time while the clock is running, as many times as the coach chooses to sent him into the game.’”
Later that decade, the term made its way from the rulebook and into broadcast parlance. Networks referred to late-season college games that weren't originally scheduled to air but were chosen to be televised due to their importance as "wild cards."
"Wild card" first appeared in professional football shortly thereafter in 1970, but not as it's used today. The league used it to describe the Denver Broncos, who were the odd team out after the merger and had to play one more cross-conference game a season because of division re-alignment. In the season after that, broadcasters and the press began referring to "the second-place team in each conference with the best winning percentage" as "wild cards," and the term stuck.