Baseball loves to talk about itself in reference to specific eras, so it's probably useful to have a way to look at how offense has changed, all in one place. Analyze1.com mapped runs, home runs, RBI, batting average, and stolen bases in Major League Baseball dating back to 1880.
Each stat is plotted when compared to their maximum and fitted across LOESS curves. For example, the yellow dot at 2000, indicates that 2000 was the year when the most home runs were hit.
While home runs increased significantly between the 1920s and 1950s, they then became more randomly distributed up until the mid-1990s, at which point homers began coming in droves with the steroid era. Home runs actually climbed through the dead ball era too, even though runs fell over that time. In fact, runs saw a slight rise after the unofficial end of the dead ball era, but dipped off again thereafter, and hit a low point in the 60s.
The chart also shows stolen bases dropped dramatically from the beginning of the game up until about 1950. Then in the 80s, steals picked up again led by guys like Rickey Henderson before dropping off in the mid-to late 1990s.
The statistic with the most consistency appears to be batting average, as demonstrated by the red curve's flatness. Batting average peaked at .309 in 1894 but has hovered around .260 for most of baseball's existence, particularly over the past 70 years. While home runs and stolen bases have fluctuated most, runs and RBIs have also shifted more than batting average throughout baseball history.