Being a slow-paced game that lends itself to easy record keeping, statistics have been kept since the beginning of professional baseball. Baseball’s first record-keeper, Harry Chadwick, created The Beadle Baseball Guide in 1861. It was the first modern sports journal.

Chadwick listed totals of games played, outs, runs, home runs, and strikeouts for hitters on important clubs. Because of his efforts, records existed in baseball before the turn of the 20th century.

Chadwick’s goal was to come up with numerical evidence that would prove what players helped or hurt a team to win. In a sense, modern baseball statistics are interpretations of data.

Baseball Card Stats

Hitting

G  –  AB  –  R  –  H  –  2B  –  3B  –  HR  –  RBI  – BB  –  SO  –  SB  –   CS  –  AVG

Pitching

W  –  L  –  ERA  –  G  –  GS  –  CG  –  ShO  –  SV  –  IP  –   HA  –  ER  –  R  –  BB  –  SO

Hitting Formulas

• AVG—Batting average: hits divided by at bats.        (H/AB)
• OBP—On base percentage: times reached base divided by at-bats plus walks plus hit by pitch plus sacrifice flies    (H+BB+HBP/AB+BB+HBP+SF).
• SLG—Slugging average: total bases divided by at-bats     (TB/AB)
• OPS—On-base plus slugging: on-base percentage plus slugging average ([H+BB+HBP/AB+BB+HBP+SF]+[TB/AB]).

Pitching Formulas

• ERA—Earned run average: earned runs, multiplied by 9, divided by innings pitched    (ER*9/IP)
• H/9—Hits per nine innings: hits allowed times nine divided by innings pitched     (H/9)
• K/BB—Strikeout-to-walk ratio: number of strikeouts divided by number of base on balls  (SO/BB)
• WHIP—Walks and hits per inning pitched: average number of walks and hits allowed per inning pitched    (BB+HA/IP)

Modern baseball statistical analysis is often referred to as Sabermetrics, and draws from a breadth of player performance measures and playing field variables. For example, hitters who hit left-handed pitchers well may receive more opportunity to face left-handed pitchers; or, some hitters or pitchers might play better against certain other players or in certain ballparks.

This ability, is measurable through statistics, and using stats to make managerial decisions is referred to as “playing the percentages.”