| Year | Player | Team(s) | ERA |
|---|---|---|---|
| 1882 | Pittsburgh Alleghenys | 1.21 | |
| 1883 | Cincinnati Red Stockings | 2.09 | |
| 1884 | Louisville Eclipse | 1.80 | |
| 1885 | St. Louis Browns | 2.07 | |
| 1886 | St. Louis Browns | 2.11 | |
| 1887 | Cincinnati Red Stockings | 2.94 | |
| 1888 | St. Louis Browns | 1.64 | |
| 1889 | St. Louis Browns | 2.25 | |
| 1890 | Louisville Colonels | 2.36 | |
| 1891 | Cincinnati Kelly's Killers | 2.45 |
| Year | Player | Team(s) | ERA |
|---|---|---|---|
| 1914 | Chicago Chi-Feds | 1.69 | |
| 1915 | Newark Pepper | 1.91 |
| Year | Player | Team(s) | ERA |
|---|---|---|---|
| 1890 | Chicago Pirates | 2.69 |
| Year | Player | Team(s) | ERA |
|---|---|---|---|
| 1890 | Cincinnati Outlaw Reds | 1.54 |
| Year | Player | Team(s) | ERA |
|---|---|---|---|
| 1871 | Chicago White Stockings | 2.73 | |
| 1872 | Boston Red Stockings | 1.98 | |
| 1873 | Athletic of Philadelphia | 1.81 | |
| 1874 | New York Mutuals | 2.30 | |
| 1875 | Boston Red Stockings | 1.52 |