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In baseball, the strike zone is the volume of space through which a pitch must pass in order to count as a strike (if the batter does not swing). The strike zone is defined as the volume of space above home plate and between the batter's knees and the midpoint of their torso. Whether a pitch passed through the zone or not is decided by an umpire, who is generally positioned behind the catcher. Strikes are desirable for the pitcher and the fielding team, as three strikes result in a strikeout. A pitch that misses the strike zone is called a ball. Balls are desirable for the batter and the batting team, as four balls allow the batter to take a base on balls. ==Definition== There is more than one set of rules that govern baseball and softball. It depends on the level and league as to which set of rules are being used. The governing bodies for the different sets of rules may have slightly different definitions. As with understanding any rule discussion, you need to know which set of rules are being referenced; Official Baseball Rules (known as OBR), Federation Rules, NCAA, Little League, ASA etc. The top of the strike zone is defined in the Major Leagues Official Rules as a horizontal line at the midpoint between the top of the batter's shoulders and the top of the uniform pants. The bottom of the strike zone is a line at the hollow beneath the kneecap. It shall be determined from the batter's stance as the batter is prepared to swing at the pitched ball. The right and left boundaries of the strike zone correspond to the edges of home plate. A pitch that touches the outer boundary of the zone is as much a strike as a pitch that is thrown right down the center. A pitch at which the batter does not swing and which does not pass through the strike zone is called a ''ball'' (short for "no ball"). The active tally of strikes and balls during a player's turn batting is called the count. In practice, the strike zone is treated as a volume of space delimited by vertical planes extending up from the pentagonal boundaries of the home plate and limited at the top and bottom by upper and lower horizontal planes passing through the horizontal lines of the definition. This volume thus takes the form of a vertical right pentagonal prism located above home plate. A pitch passing outside the front of the defined volume of the strike zone but curving so as to enter this volume farther back (without being hit) is described as a "back-door strike". Major League Baseball has occasionally increased or reduced the size of the strike zone in an attempt to control the balance of power between pitchers and hitters.〔(【引用サイトリンク】title=1968: Year of the Pitcher )〕 After the record home run year by Roger Maris in , the major leagues increased the size of the strike zone from the top of the batter's shoulders to the bottom of his knees. In , pitchers such as Denny McLain and Bob Gibson among others dominated hitters, producing 339 shutouts.〔 Carl Yastrzemski would be the only American League hitter to finish the season with a batting average higher than .300.〔 In the National League, Gibson posted a 1.12 earned run average, the lowest in 54 years, while Los Angeles Dodgers pitcher Don Drysdale threw a record 58 and two-thirds consecutive scoreless innings during the 1968 season.〔 As a result of the dropping offensive statistics, Major League Baseball took steps to reduce the advantage held by pitchers by lowering the height of the pitcher's mound from 15 inches to 10 inches, and by reducing the size of the strike zone for the season. Although the ''de facto'' enforced strike zone can vary, the official rules (Rule 2.00, A STRIKE (b)) define a pitch as a strike "if any part of the ball passes through any part of the strike zone." A batter who accumulates three strikes in a single batting appearance has struck out and is ruled out (with the exception of an uncaught third strike); a batter who accumulates four balls in a single appearance has drawn a base on balls (or ''walk'') and is awarded advancement to first base. In very early iterations of the rules during the 19th century, it took up to 9 balls for a batter to earn a walk; however, to make up for this, the batter could request the ball to be pitched high, low, or medium. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Strike zone」の詳細全文を読む スポンサード リンク
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