GIDP

In baseball, a double play (denoted as DP in baseball statistics) is the act of making two outs during the same continuous play. Double plays are relatively common, as they can occur any time there is at least one baserunner and less than two outs.

During the 2016 Major League Baseball (MLB) regular season, the league average for double plays completed by each team during the course of a 162-game season was 145 – nearly one per game by each team.

The simplest scenario for a double play is a runner on first base with less than two outs. In that context, four example double plays are:

The force double play is the most commonly seen double play, however double plays can occur in many ways in addition to the noted examples, and can involve many combinations of defensive players or even special circumstances (for example, interference).

Per standard baseball positions, the examples given above would be recorded, respectively, as:

Double plays that are initiated by a batter hitting a ground ball are recorded in baseball statistics as GIDP (grounded into double play) – this statistic has been tracked since 1933 in the National League and since 1939 in the American League.

Highly desirable to the fielding team and highly undesirable to the batting team, a double play can prove critical to the outcome of a specific game. The fielding team is likely to change pitch selection and defensive alignment to try and get a batter to ground into a force double play. Pitchers may throw pitches more likely to be hit as a ground ball – such as a sinker – while fielders can be positioned to make a ground ball more likely to be turned into a double play. Likewise, the batting team may take action – such as a hit and run play – to reduce the chance of grounding into a force double play.

In baseball slang, making a double play is referred to as "turning two" or a "twin killing". Double plays are also known as "the pitcher's best friend" because they disrupt offense more than any other play, except for the rare triple play. A force double play made on a ground ball hit to the third baseman, who throws to the second baseman, who then throws to the first baseman, is referred to as an "around the horn" double play. A "strike 'em out, throw 'em out" double play occurs when a base runner is caught stealing immediately after the batter strikes out. The ability to "make the pivot" on a force double play – receiving a throw from the third base side, then quickly turning and throwing to first base – is a key skill for a second baseman.

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Wikipedia