Cork Gaines wrote about the HR trend in baseball since testing started for performance enhancing drugs. He presented a chart of the trend (surprising effective given his past charts), but he never answered his own question….is testing working?
One way to determine the answer is through comparisons to other statistics.
I downloaded the season averages across both leagues and MLB in total from baseball-reference and built this interactive analysis. The stats are order by batting stats then pitching stats.
This viz allows you to compare home runs to many other statistics through the selectors at the top right. In addition you can:
- View any two statistics to look for trends by choosing a primary measure and a comparison
- Filter the time frame to all years, the pre-testing era, and the testing era (1993+)
- Filter the leagues to focus your analysis
- Click on a league at the bottom to highlight that league
In this initial view of HR vs. ERA, I see a couple of things:
- HR are on a slow descent in the testing era, especially since 2000
- ERA is in a similar decline, possibly indicating that improved pitches has had as much of an impact as testing
- Batting Average has remained flat. This means that the reduction in HR has not impacted BA.
- Teams are simply scoring fewer runs, likely due to the reduction in long balls
- The trend in complete games is despicable
What do you see? Play around with the different stats and see if you can draw any conclusions.