| ERA+; Year | Pitcher | actual ERA; league ERA |
| 291; 2000 | |
| 279; 1914 | |
| 274; 1994 | |
| 262; 1995 | |
| 259; 1913 | |
| 258; 1968 | |
| 253; 1906 | |
| 243; 1912 | |
| 243; 1999 | |
| 230; 1905 | |
| 229; 1985 | |
| 226; 2005 | |
| 225; 1915 | |
| 222; 1997 | |
| 222; 1909 | |
| 220; 1931 | |
| 219; 1997 | |
| | ERA+; Year | Pitcher | actual ERA; league ERA |
| 217; 1996 | |
| 217; 1901 | |
| 216; 1907 | |
| 215; 1919 | |
| 214; 1918 | |
| 213; 1990 | |
| 213; 1907 | |
| 211; 2003 | |
| 209; 1905 | |
| 209; 1902 | |
| 208; 1978 | |
| 206; 1908 | |
| 205; 2009 | |
| 202; 2002 | |
| 201; 1923 | |
| 200; 1955 | |
|