Strike zone - wikipedia Strike zone For other uses, see Strike zone ( disambiguation ). A labelled drawing of the strike zone superimposed onto an image from a game, showing a batter, catcher and umpire. The batter attempts to hit a baseball pitched by the pitcher ( not pictured ) to the catcher ; and the umpire decides whether pitches are balls or strikes. 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 of that batter. A pitch that misses the strike zone is called a ball ( only if batter does n't swing ). Balls are desirable for the batter and the batting team, as four balls allow the batter to take a `` walk '' to first base as a base on balls. Contents 1 Definition 2 Enforcement 3 See also 4 References 5 Further reading 6 External links 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. The top of the strike zone is defined in the Major League 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, both 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 above. 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. After the record home run year by Roger Maris in 1961, 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 1968, 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 1969 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. Enforcement While baseball rules provide a precise definition for the strike zone, in practice, it is up to the judgement of the umpire to decide whether the pitch passed through the zone. Rule 9.02 of the Official Baseball Rules states that objections to judgment calls on the field, including balls and strikes, shall not be tolerated, and that any manager, coach, or player who leaves his dugout or field position to contest a judgement call will first be warned, and then ejected. Many umpires, players and analysts, including the authors of a University of Nebraska study on the subject, believe that due to the QuesTec pitch - tracking system, the enforced strike zone in 2002 -- 2006 was larger compared to the zone in 1996 -- 2000 and thus closer to the rulebook definition. Some commentators, such as Tim Roberts of covers.com, believe that the zone has changed so much that some pitchers, such as Tom Glavine, have had to radically adjust their approach to pitching for strikes. In 2003, a frustrated Curt Schilling took a baseball bat to a QuesTec camera and destroyed it after a loss, saying the umpires should n't be changing the strike zone to match the machines. In 2009, a new system called Zone Evaluation was implemented in all 30 Major League ballparks, replacing the QuesTec system ; the new system records the ball 's position in flight more than 20 times before it reaches home plate. Much of the early resistance from Major League umpires to QuesTec had diminished and the implementation of the new Zone Evaluation system in all the parks went largely unnoticed. Like the old system, the new system will be used to grade umpires on accuracy and used to determine which umpires receive postseason assignments. See also Baseball portal Glossary of baseball References ^ Jump up to : `` 1968 : Year of the Pitcher ''. thisgreatgame.com. Retrieved 25 December 2011. Jump up ^ `` Expanded strike zone unveiled ''. The Press - Courier. Associated Press. 8 March 1963. p. 9. Retrieved 25 December 2011. Jump up ^ `` McLain Says Lower Mound Will Take Toll of Pitchers ''. The Telegraph - Herald. Associated Press. 14 January 1969. p. 13. Retrieved 25 December 2011. Jump up ^ ( 1 ) Jump up ^ Newswise Social and Behavioral Sciences News Larger Strike Zone, Drug Testing Reduced Hitting in Baseball Since 2000 Jump up ^ Umpires and totals : Men behind the mask occasionally steal the show Jump up ^ D'backs ' Schilling fined for destroying QuesTec camera Jump up ^ Monitor May Reopen Wounds, an April 2009 article from The New York Times Jump up ^ Preview 2009 : The umpires ' arbiter from an April 2009 Star Tribune article Further reading Gammons, Peter ( April 6, 1987 ). `` What Ever Happened to the Strike Zone ? ''. Sports Illustrated. 66 ( 14 ) : 36 -- 40, 45 -- 46. External links 2001 Changes in Strike Zone St. Petersburg Times article. Strike Zone MLB website. John Walsh, `` Strike Zone : Fact vs. Fiction '', The Hardball Times, July 11, 2007 The Strike Zone : A Chronological Examination of the Official Rules baseball - almanac Baseball concepts Outline, Glossary Rules Rules of baseball Ground rules Infield fly rule Interference Field Backstop Baseball diamond Batter 's box Batter 's eye Bullpen Dugout Foul pole Foul territory Infield On - deck circle Outfield Warning track Equipment Ball Bat Batting cage Batting glove Batting helmet Cap Doughnut Glove ( defense ) Pitching machine Protective cup Shin guard Stirrups Uniform Uniform number Game process Batting order Extra innings Innings On - deck Out Positions Run Seventh - inning stretch Batting At bat Baltimore chop Bat flip Chinese home run Batting count Bunt Checked swing Cleanup hitter Designated hitter Double Double switch Foul ball Foul tip Golden sombrero Grand slam Ground rule double Hat trick Hit Hit and run Hit by pitch Hitting for the cycle Home run Infield hit Inside - the - park home run Leadoff hitter Lefty - righty switch Line drive Moonshot Plate appearance Platoon system Pull hitter Sacrifice bunt Sacrifice fly Single Slap bunt Strikeout Strike zone Sweet spot Switch hitter Triple Walk Walk - off home run Pitching Balk Beanball Breaking ball Brushback pitch Changeup Curveball Eephus Fastball Full count Inside pitching Intentional walk Knuckleball No - hitter Passed ball Perfect game Pitch count Pitchout Quick pitch Screwball Shutout Slider Spitball Strikeout Striking out the side Time of pitch Wild pitch Base running Balk Bases loaded Caught stealing Contact play Hit and run Left on base Obstruction Safe Scoring position Slide Small ball Squeeze play Stolen base Tag up Fielding ( positioning ) Appeal play Assist Blocking the plate Catch Defensive indifference Double play Error Fielder 's choice Fifth infielder Force play Fourth out Hidden ball trick In - between hop Infield fly rule Infield shift Interference Pickoff Putout Rundown Tag out Triple play unassisted Uncaught third strike Wall climb Wheel play Miscellaneous Baseball statistics Bench jockey Bench - clearing brawl Dead ball Jargon In flight Pepper Scorekeeping Series Shagging Slump Streak ( losing ) Streak ( winning ) Portal WikiProject Retrieved from `` https://en.wikipedia.org/w/index.php?title=Strike_zone&oldid=799946411 '' Categories : Batting ( baseball ) Baseball pitching Baseball terminology Baseball rules Hidden categories : All articles with unsourced statements Articles with unsourced statements from June 2009 Talk Contents About Wikipedia Dansk Deutsch Français 한국어 Nederlands 日本 語 Polski Simple English Svenska Edit links This page was last edited on 10 September 2017, at 19 : 21. 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Question: who calls the pitches in major league baseball
Answer: umpire