From BR Bullpen
The second baseman (abbreviated 2B and position 4 when scoring) is an infielder who normally plays close to and on the right field side of second base. Second base is a key defensive position, often ranked just behind shortstop in terms of difficulty.
The second baseman has responsibilities different from any other infielder. Like the shortstop and third baseman, the second baseman must be agile and able to start and stop quickly. The second baseman is usually the pivot man on double plays started by the shortstop and third baseman and occasionally on plays started by the catcher, pitcher, or first baseman. The second baseman normally covers second base on stolen base attempts against batters who hit primarily to the left side of the field. He also covers first base on plays like bunts that require the first baseman to move far from the bag. Second basemen are typically involved in more fielding plays than any other fielder except for the catcher, who is considered to make a fielding play on every strikeout.
The only fielding ability that is not really required for second basemen is a strong throwing arm. Because the second baseman's position is closer to first base than the shortstop's or third baseman's, he is not required to have as strong an arm as the other infielders.
-  Article on power-hitting second basemen and shortstops in The Hardball Times.
|Outfielders:||Left field | Center field | Right field|
|Infielders:||3rd base | Shortstop | 2nd base | 1st base|