The average Baseball remains in play for only five to seven pitches in a Major League game. After the game the baseballs that are taken out of play are used for batting, and fielding practice. Approximately 600,000 baseballs are used by all Major League teams combined during the course of a season. -Steven KeyMan
Chat with our AI personalities
They are kept until the end of the game (although some umpires re-introduce balls with undetectable blemishes back into the game, without the pitcher's or catcher's knowledge). At the end of the game they are returned to the home team, who will add them to the batting practice stock or will send them down to their minor league teams for their use.
They are either cleaned and reuesed or used for batting practice. If the condition is bad enough they will be destroyed and used to make new balls.
If it's just any old baseball that isn't significant, then usually the players just toss them into the stands. If you get front row seats, just ask for one of them to toss one to you.
Used balls get pitched in batting practice; unused balls go back in the bag for the next game.