Before 1994, there had been only one. Although Rawlings, the manufacturer, denies changing the ball, some people suspect conspiracy. But there are other explanations. In the intimate new ballparks, outfield fences are closer. And foul territory is smaller, so more batters get to keep swinging after hitting a pop foul.
Players are bigger.
Expansion has diluted pitching. And one of the many curses of the designated hitter rule is that many fine athletes do not want to be pitchers because they want to bat. No umpire, not one, consistently calls the strike zone as the rule book defines it. Many batters wear armor on the arm closest to the pitcher so they can crowd the plate, taking the outside corner away from the pitcher. And if the pitcher throws inside to drive the batter back, the batter, being a modern man, sensitive and vulnerable and all that, throws a tantrum.