Modern baseball judges players with several statistics. Batting average is a batter's hits divided by his times at bat, and slugging percentage is total bases per at-bat: (singles + 2 x doubles + 3 x triples + 4 x home runs) divided by at-bats. On-base percentage was invented in the 1940s-50s by Dodgers executive Branch Rickey and statistician Allan Roth, and did not become an official statistic until 1984. The save was first defined with specific rules by writer Jerome Holtzman in the early 1960s and became an official statistic in 1969. Another tool is the box score: in 1859 Henry Chadwick wrote the first modern box score, which recorded runs, hits, putouts, assists and errors, and marked pitchers' strikeouts with the letter K. Earned run average (ERA), the number of earned runs a pitcher allows per nine innings, measures a pitcher's performance.
Some careers stand out on those scales. Babe Ruth hit 714 home runs in his major league career, and his career on-base plus slugging (OPS) of 1.164 ranks first all-time in the American and National leagues, as of November 2026. Hank Aaron finished his career with 755 home runs. Cy Young pitched the first perfect game of the 20th century on May 5, 1904, and threw three no-hitters in his career. As of November 2026, his 511 wins are almost 100 more than any other pitcher in history. Cal Ripken Jr.'s streak of 2,632 straight games, which began on May 30, 1982, is the longest by anyone in baseball history, as of November 2026. On the bases, Rickey Henderson broke Ty Cobb's 65-year-old American League record of 96 stolen bases with 100 in 1980.
Next, consider what happens during an individual pitch. The pitching rubber is 60 feet, 6 inches from home plate, and a pitch must cross the strike zone, the area over home plate between the middle of the batter's body and the kneecaps, to be called a strike. A spinning baseball curves because of the Magnus force, and it breaks in the direction that the leading edge of the ball is turning. An overhand fastball has backspin, so the Magnus force pushes it up and it drops less than gravity alone would make it drop; an overhand curveball has topspin and drops more. You may have heard that a curveball only looks like it curves. In fact, a spinning baseball really does curve, because of the Magnus force.
Spin can also be measured precisely. Spin rate is measured in revolutions per minute, and a fastball with a high spin rate crosses the plate a few inches higher than one with a lower spin rate at the same speed. A pitched baseball also loses approximately 10 percent of its speed on the way to the plate, so a pitch that leaves the hand at 95 mph crosses the plate at approximately 86 mph. Afterward, the batter makes contact with the baseball. Exit velocity is the speed of the baseball as it comes off the bat right after contact, and a faster ball gives the defense less time to react. Launch angle is the vertical angle at which the ball leaves the bat: under 10 degrees is a ground ball, 10 to 25 a line drive, 25 to 50 a fly ball and over 50 a pop up.
All of this depends on the ball itself; a Major League baseball has a cork core with two layers of rubber, wool yarn wound around it, and a cover that workers stitch on by hand. It has 108 double stitches, weighs 5 to 5.25 ounces and measures 9 to 9.25 inches around. Major League baseballs have flat seams, and college teams switched to flat-seamed balls after the NCAA concluded a study on ball seams in 2015. Statcast calls a batted ball a Barrel when its exit velocity and launch angle have led to at least a .500 batting average and 1.500 slugging percentage since 2015. Air drag takes a lot of distance off a long fly ball: one that carries 400 feet would carry approximately 700 feet if there were no drag.
Words to know
- Magnus: spin-push force
- backspin: spin upward
- topspin: spin downward
- Statcast: tracking system
- seams: stitched edges
