After the 1994 season was abruptly ended in August with no World Series because of a dispute between owners and players, fans were very upset. A big part of the cure was a big increase in home runs, apparently aided by performance enhancing drugs (PED), including steroids.
Attendance reached new heights, so a blind eye was turned.
Part of the effort to placate fans attending games was to reverse a long established practice of conserving baseballs. Instead of making fans return balls, they were allowed to keep them. Players were even now allowed to throw baseballs into the stands. Ball boys and girls would hand them to fans. Many baseballs were given away.
Result: the pitchers had a new ball much more often than ever before. A new ball is more lively than one that has been in play.