Before a baseball game, each team has to "muddy" the balls that are going to be used. This is a process that has been done for many years to take the shine off new balls so pitchers have a better grip when playing.
So each team in the league must muddy the balls using Delaware state mud that is shipped in cans. However, a thorough study showed that each team uses different techniques to muddy the balls.
Now, to guarantee that all the balls used have the same characteristics, the MLB established a new rule to standardize the technique used in each stadium. On the other hand, changes were also made to the procedure for storing the balls. All this as an effort to achieve the greatest possible uniformity in all the balls used in the league.