In the current age of baseball a 25-man roster is not enough. Teams have an active 25-man roster each night, yes, but there are also a handful of players in Triple-A who shuttle back and forth as needed. New middle relievers are brought in almost daily and teams even swap out bench players for matchup purposes going into a series. There’s the 25-man roster and a Triple-A taxi squad.
Last season 49 different players appeared in a game for the Yankees, and that doesn’t include Ryan Bollinger and Domingo Acevedo, who were called up for a day (twice, in Bollinger’s case) but did not appear in a game.