The shortstop positions himself between the third baseman and the second-base bag.
On defense: The shortstop is considered the captain of the infield and takes charge on balls hit in the air as well as communication among infielders. If both the shortstop and third baseman are attempting to field the same batted ball, the shortstop will often call off the third baseman.
Shortstops are an integral component of turning double plays. On balls hit to the left side of the infield, a shortstop must cleanly field the ball and accurately throw it to the second baseman covering the second-base bag. On a ball hit to the right side of the infield, the shortstop must cover the second-base bag and receive a throw from either the second baseman or, less frequently, the first baseman and make an accurate relay throw to first. Shortstops will typically cover the second-base bag on grounders hit back to the pitcher in double-play situations, as well.
A good defensive shortstop must possess excellent range, a strong throwing and an ability to field batted balls cleanly. The shortstop position is widely considered the most valuable defensive position in the infield, if not on the entire field of play.
On offense: Shortstop is widely considered to be the most important and demanding defensive position on the field, save for catcher. Given the difficulty of finding strong defensive shortstops, the possession tends to have some of the game's less-imposing hitters. With this in mind, shortstops capable of contributing strong defense and offense are considered to be among the most valuable player assets in all of baseball.