The balls used during Major League Baseball games are recycled into batting practice balls or sent to the minor leagues after the conclusion of each contest. The notion is that scuffs and dents on the surface may adversely affect the trajectory of the ball and the pitcher's grip.
Since balls are frequently fouled off into the stands by batters and usually discarded after hitting the dirt, the average baseball has a game life of just a few pitches. Even balls that remain in play are often inspected by umpires if they are hit hard enough. An estimated eight to 10 dozen balls are used in a nine-inning game.