Managers love players who can move around the diamond. Having such flexibility allows them to give tired or injured players days off, while keeping a productive bat in the lineup.
The ability to learn a new position opens up many opportunities for players as well. Aging shortstops may prolong their careers by moving to second or third base. A la Cal Ripken Jr. A team might also employ multiple impact players with the same natural position if one of them is able to learn a secondary spot, like when Alex Rodriguez moved to New York, where Derek Jeter was entrenched at shortstop.
These slides will not include players who only play outfield and have merely moved between outfield spots. Nor will they include catchers who play occasional games at first base to rest their knees.