Trends in MLB

While triples per game has descended from 0.5 at the turn of the century to just over 0.2 in present day, doubles have almost doubled during the same time range. Why? It seems like size/shape of ballparks would have something to do with it as well as relative running speed of batter to outfielder's arm. The next plot is a little more obvious: homeruns have increased 5x over the century to more than 1 per game in recent times while strikeouts have also increased. Recent times, when steroids were at their highest level of use, batters were swinging for the fences more than ever before, accentuating the trend. It also indicates the evolution of the game on a longer time scale: while fielding and base running were the primary tenet of focus earlier in baseball's lifetime, an increasing focus on the dual between the pitcher and the batter drives both player's kpi upward. Hits per game, batting average, runs per game and walks per game are all fairly flat over time.