From BR Bullpen
Fielding is one of the four fundamental aspects of the game of baseball, along with batting, pitching and baserunning. The object of fielding is to catch a live ball and to try to put either the batter and/or one or more baserunners out.
 The Fielders
While there is only one batter and one pitcher at any time, there are always nine fielders. These usually occupy standard positions on the field. Those are:
- One pitcher (P), who stands on the pitcher's mound. Note that he is only considered a fielder once he has thrown a pitch.
- One catcher (C), who crouches in foul territory, behind the batter.
- Four infielders - the first baseman (1B) and the third baseman (3B) who occupy positions close to their respective bases, and the second baseman (2B) and the shortstop (SS) who stand respectively between first and second base, and second and third base.
- Three outfielders who are called the left fielder (LF), the centerfielder (CF) and the right fielder (RF), named from the batter's perspective.
When fielders are playing in positions different than this standard layout, it is known as a defensive shift. The designated hitter (DH) is a unique position, as he cannot occupy a fielding position, and when he is used as a fielder in the course of a game, he loses his status as the DH.
|Outfielders:||Left field | Center field | Right field|
|Infielders:||3rd base | Shortstop | 2nd base | 1st base|
 Fielding Plays
 Fielding pitches
The first fielding play in a game is for the catcher to catch the pitch. Failure to catch the pitch can have important consequences in the following two situations:
- if the pitch is the third strike and first base is open or there are two outs, the batter is not out and can run to first base (see: dropped third strike);
- if there are one or more baserunners, they can attempt to advance one or more bases.
In any other situation, a pitch that is not fielded properly has no consequence.
 Fielding batted balls
Most fielding plays occur after the batter has hit a ball in play (but not necessarily in fair territory).
- If the ball is hit in the air, as a fly ball or as a line drive, the fielders will attempt to catch it before it hits the ground. If they are successful, the batter is out, and baserunners must return to their bases before attempting to advance;
- If the ball is hit on the ground, as a ground ball, the fielders will attempt to catch it and either to throw to another fielder touching one of the bases to put out the batter or a baserunner, or to tag the batter or a baserunner with the ball.
If a ball is batted in a way that makes it impossible to put out either the batter or a baserunner, the fielders will attempt to limit their advance to the fewest possible bases.
 Fielding on baserunning plays
Fielding also comes into play on baserunning attempts:
- The first baseman or other infielders must catch any throws from the pitcher or catcher which are aimed at picking a baserunner off a base;
- The catcher will throw to the appropriate base to attempt to put out a runner attempting a stolen base or attempting to advance on a wild pitch or a passed ball; if the baserunner is trying to advance to home plate, the catcher will try to tag him himself, or to throw to another player covering home plate.
In all of the types of plays outlined above, failure to execute a fielding play will usually result in an error (or a passed ball in the case of a pitch that is not fielded properly).
 Fielding statistics
The following statistics are compiled for all fielders:
- Putouts count the number of times a fielder has recorded an out himself. Note: in the case of a strikeout, the putout is attributed to the catcher, unless he fails to catch the third strike (see above); in the case of an out where no fielder touches the ball (e.g. as a result of interference or a batted ball hitting a baserunner in fair territory), the putout is awarded to the nearest fielder.
- Assists count the number of times a fielder has participated in an out by relaying or deflecting a batted ball. For example, in the case of a batter out on a ground ball from the shortstop to the first baseman, the shortstop is credited with an assist and the first baseman with a putout. Note: in this case, the shortstop would receive credit for an assist even if the first baseman dropped his throw and no out was recorded if, in the opinion of the official scorer, the throw was catchable and would have resulted in an out if caught.
- Errors count the number of plays on which, as a result of a misplay by a fielder, a batter or runner is safe when he should normally have been put out, or advances at least one more base than he would have if the play had been executed as intended.
- Total chances are the number of times a fielder has an opportunity to make or contribute to an out. They are calculated by adding putouts, assists and errors.
- Chances accepted is the total number of plays that a player made successfully. It is calculated by adding putouts and assists.
- Double plays and triple plays are plays on which more than one out is recorded.
- Fielding percentage is the fraction of plays that a fielder makes successfully, and is calculated by dividing chances accepted by total chances. It is used to measure how likely a player is to make an error.
- In addition, there are fielding statistics specific to catchers: number of passed balls, number of stolen bases attempted and number of runners caught stealing.
These statistics are very blunt and only indirectly reflect a player's fielding ability. This is why a number of sabermetricians have devised advanced fielding metrics over recent years, such as zone rating, UZR, and others.
 Further Reading
- Jason Aronoff: Going, Going... Caught!: Baseball's Great Outfield Catches as Described by Those Who saw Them, 1887-1964, McFarland, Jefferson, NC, 2009.
- Dan Basco and Jeff Zimmerman: "Measuring Defense: Entering the Zones of Fielding Statistics", in The Baseball Research Journal, SABR, Volume 39, Number 1 (Summer 2010), pp. 83-97.
- Thomas Boswell: "Nine Against One", in Why Time Begins on Opening Day, Penguin Books, New York, NY, 1984, pp. 239-246.
- Jon Bruschke: "A Manifesto for Defensive Baseball Statistics", in The Baseball Research Journal, Number 36 (2007), SABR, Cleveland, OH, pp. 99-108.
- Jon Bruschke: "The Bible and the Apocrypha: Saved Runs and Fielding Shares", The Baseball Research Journal, SABR, Volume 41, Number 1 (Spring 2012), pp. 12-19.
- Dick Cramer: "Preventing Base Hits: Evidence that Fielders Are More Important Than Pitchers", in The Baseball Research Journal, SABR, Number 31, University of Nebraska Press, Lincoln, NE, 2003, pp. 88-92.
- John Dewan: The Fielding Bible: Break-Through Analysis of Major League Baseball Defense by Team and Player, ACTA Publications, Skokie, IL, 2006.
- Vince Gennaro: "The Hidden Value of Glovework", in The Baseball Research Journal, SABR, Volume 39, Number 1 (Summer 2010), pp. 98-102.