This link provides a long but comprehensive account of the various ebbs and flows of runs scored over the years. One very significant factor: the strike zone was enlarged in 1963.Here are the cumulative totals of the ten highest ten run producing seasons (with games played in parenthesis) for each of the following 3B:
The above only includes the seasons where each respective player played the majority of games as a 3B (NYY years for ARod, not Brett's 1B nor Jones OF years).
- Traynor 1898 (1447)
- Jones 1744 (1458)
- Schmidt 1742 (1546)
- Mathews 1708 (1489)
- ARod 1683 (1400)
- Brett 1641 (1402)
No doubt, there were different rates of scoring in various eras.
Run totals throughout baseball history – Baseball: Past and Present
baseballpastandpresent.com