⚾Teams

No one person did, and specifically not Abner Doubleday — the Cooperstown creation story was manufactured by the 1907 Mills Commission on flimsy testimony, and Doubleday, a West Point cadet in 1839, never mentioned baseball in his writings. The game evolved from English bat-and-ball sports like rounders through American variants such as town ball; a 1791 bylaw in Pittsfield, Massachusetts already banned 'base ball' near the town meeting house. The decisive codification came from the Knickerbocker Base Ball Club of New York, whose 1845 rules — foul territory, three-out innings, tagging runners rather than throwing the ball at them — are the recognizable ancestor of the modern game. Alexander Cartwright, a Knickerbocker member, is the conventional individual credit, though historians now view even his role as shared with clubmates.

The 1845 Knickerbocker Rules had no fixed length — games ended when one side scored 21 'aces' (runs), usually taking about six innings. As pitching improved and scoring dropped, games dragged unpredictably, so an 1857 convention of sixteen New York clubs standardized the format: nine players per side and nine innings per game, with extra innings breaking ties. The choice of nine appears to have followed the roster size — nine positions, nine innings — rather than any deeper logic. The framework has proven nearly untouchable ever since: the only structural modifications in 165-plus years are the 2020 introduction of the extra-innings automatic runner on second base and the use of seven-inning games in doubleheaders during the 2020-21 pandemic seasons, the latter since abandoned at the major league level.

The physics leaves almost no margin. A 95 mph fastball covers the 60 feet 6 inches from release to plate in roughly 0.4 seconds; accounting for the time a swing takes, the hitter must decide to commit when the ball is about halfway home, effectively predicting its final location. A few milliseconds of timing error or a quarter inch of contact error turns a home run into a pop-up, and modern pitchers layer 3,000-rpm breaking balls that tunnel with the fastball before diverging. The outcome data makes the case: the best hitters alive fail about 70 percent of the time, no one has batted .400 over a season since Ted Williams's .406 in 1941, and the league as a whole hit around .243 in 2024 against average fastballs of 94 mph.

Structurally, almost nothing anymore. The National League (founded 1876) and American League (major status from 1901) operated as legally separate leagues with their own presidents and umpires until MLB centralized in 2000, and interleague play only began in 1997. The famous on-field difference — the AL's designated hitter batting for the pitcher, adopted in 1973, while NL pitchers still hit — ended when the 2022 collective bargaining agreement made the DH universal. Today the leagues function as conferences: 15 teams each across three divisions, meeting in the All-Star Game and World Series. The identities persist culturally (the AL's historically offense-first reputation, old rivalries), and league affiliation still determines playoff bracketing, but a fan watching two games today will find no difference in rules between them.

Wins Above Replacement estimates how many wins a player adds compared with a freely available minor league fill-in at the same position. It converts everything a player does — hitting, baserunning, fielding, position difficulty, and for pitchers, run prevention — into runs, then into wins, using the well-established relationship of about ten runs per win. Its power is comparability: WAR can weigh a slugging first baseman against a defense-first shortstop, or a 1920s outfielder against a modern one, because each is measured against his own league's baseline. Rules of thumb: 2 WAR is a solid starter, 5 is All-Star level, 8-plus is an MVP season, and career totals above 60 fuel Hall of Fame cases. Versions differ — Baseball-Reference and FanGraphs calculate pitching and defense differently — so serious analysis cites which WAR it means.

Twenty-four in over 240,000 major league games — a pitcher facing exactly 27 batters and retiring every one, allowing no hit, walk, hit batter, or error. The most recent was Domingo Germán of the Yankees on June 28, 2023, an 11-0 win at Oakland, ending a drought since 2012, which had been an anomalous boom year with three. The most famous remains Don Larsen's in Game 5 of the 1956 World Series, still the only postseason perfect game. The near-misses are their own genre: Armando Galarraga lost one in 2010 to an admitted umpire error on the 27th out, and Harvey Haddix threw 12 perfect innings in 1959 only to lose the game in the 13th. Rising strikeout rates should make perfection more attainable, yet five-and-dive starter usage means fewer pitchers are even allowed to try for 27 outs.