In Major League Baseball, the winning pitcher is defined as the pitcher who last pitched prior to the half-inning when the winning team took the lead for the last time.[1] There are two exceptions to this rule. The first is that a starting pitcher must complete five innings to earn a win (four innings for a game that lasts five innings on defense). If he fails to do so, he is ineligible to be the winning pitcher even if he last pitched prior to the half-inning when his team took the lead for the last time, and the official scorer awards the win to the relief pitcher who, in the official scorer's judgment, was the most effective. The second exception applies if the relief pitcher who last pitched prior to the half-inning when the winning team took the lead for the last time was "ineffective in a brief appearance" in the official scorer's judgment, in which case the win is awarded to the succeeding relief pitcher who, in the official scorer's judgment, was the most effective.[2]
Charles Radbourn[3] holds the record for the most wins in a single-season, winning 59 games in 1884.[4] John Clarkson[5] (53 in 1885) and Guy Hecker[6] (52 in 1884) are the only other pitchers to win more than 50 games in a single-season.[7]
| Rank | Rank amongst leaders in single-season wins. A blank field indicates a tie. | |
| Player | Name of player. | |
| W | Total single-season wins. | |
| Year | Season wins were recorded. | |
| Denotes elected to National Baseball Hall of Fame. |
| Rank | Player | W | Year | |
|---|---|---|---|---|
| 1 | Old Hoss Radbourn * | 59 | 1884 | |
| 2 | John Clarkson * | 53 | 1885 | |
| 3 | Guy Hecker | 52 | 1884 | |
| 4 | John Clarkson * | 49 | 1889 | |
| 5 | Charlie Buffinton | 48 | 1884 | |
| Old Hoss Radbourn * | 48 | 1883 | ||
| 7 | Albert Spalding * | 47 | 1876 | |
| John Montgomery Ward * | 47 | 1879 | ||
| 9 | Pud Galvin * | 46 | 1883 | |
| Pud Galvin * | 46 | 1884 | ||
| Matt Kilroy | 46 | 1887 | ||
| 12 | George Bradley | 45 | 1876 | |
| Silver King | 45 | 1888 | ||
| Jim McCormick | 45 | 1880 | ||
| 15 | Bill Hutchison | 44 | 1891 | |
| Mickey Welch * | 44 | 1885 | ||
| 17 | Tommy Bond | 43 | 1879 | |
| Larry Corcoran | 43 | 1880 | ||
| Billy Taylor | 43 | 1884 | ||
| Will White | 43 | 1879 | ||
| Will White | 43 | 1883 | ||
| 22 | Lady Baldwin | 42 | 1886 | |
| Tim Keefe * | 42 | 1886 | ||
| 24 | Jack Chesbro * | 41 | 1904 | |
| Dave Foutz | 41 | 1886 | ||
| Bill Hutchison | 41 | 1890 | ||
| Tim Keefe * | 41 | 1883 | ||
| Ed Morris | 41 | 1886 | ||
| Charlie Sweeney | 41 | 1884 | ||
| 30 | Tommy Bond | 40 | 1877 | |
| Tommy Bond | 40 | 1878 | ||
| Bob Caruthers | 40 | 1885 | ||
| Bob Caruthers | 40 | 1889 | ||
| Jim McCormick | 40 | 1884 | ||
| Bill Sweeney | 40 | 1884 | ||
| Ed Walsh * | 40 | 1908 |
| Rank | Player | W | Year | |
|---|---|---|---|---|
| Will White | 40 | 1882 | ||
| 38 | Ed Morris | 39 | 1885 | |
| John Montgomery Ward * | 39 | 1880 | ||
| Mickey Welch * | 39 | 1884 | ||
| 41 | John Clarkson * | 38 | 1887 | |
| Kid Gleason | 38 | 1890 | ||
| Toad Ramsey | 38 | 1886 | ||
| 44 | Pud Galvin * | 37 | 1879 | |
| Tim Keefe * | 37 | 1884 | ||
| Jack Lynch | 37 | 1884 | ||
| Christy Mathewson * | 37 | 1908 | ||
| Toad Ramsey | 37 | 1887 | ||
| Jim Whitney | 37 | 1883 | ||
| 50 | John Clarkson | 36 | 1886 | |
| Bill Hutchison | 36 | 1892 | ||
| Walter Johnson * | 36 | 1913 | ||
| Frank Killen | 36 | 1893 | ||
| Jim McCormick | 36 | 1882 | ||
| Sadie McMahon | 36 | 1890 | ||
| Tony Mullane | 36 | 1884 | ||
| Amos Rusie * | 36 | 1894 | ||
| Cy Young * | 36 | 1892 | ||
| 59 | Larry Corcoran | 35 | 1884 | |
| Jim Devlin | 35 | 1877 | ||
| Tim Keefe | 35 | 1887 | ||
| Tim Keefe | 35 | 1888 | ||
| Silver King | 35 | 1889 | ||
| Joe McGinnity * | 35 | 1904 | ||
| Sadie McMahon | 35 | 1891 | ||
| Tony Mullane | 35 | 1883 | ||
| Kid Nichols * | 35 | 1892 | ||
| Ed Seward | 35 | 1888 | ||
| Jack Stivetts | 35 | 1892 | ||
| Cy Young * | 35 | 1895 | ||
| 71 | Larry Corcoran | 34 | 1883 | |
| George Haddock | 34 | 1891 |
| Rank | Player | W | Year | |
|---|---|---|---|---|
| Ed Morris | 34 | 1884 | ||
| Kid Nichols * | 34 | 1893 | ||
| Mike Smith | 34 | 1887 | ||
| Scott Stratton | 34 | 1890 | ||
| Mickey Welch * | 34 | 1880 | ||
| Will White | 34 | 1884 | ||
| Smoky Joe Wood | 34 | 1912 | ||
| Cy Young * | 34 | 1893 | ||
| 81 | Grover Cleveland Alexander * | 33 | 1916 | |
| Mark Baldwin | 33 | 1890 | ||
| John Clarkson * | 33 | 1888 | ||
| John Clarkson * | 33 | 1891 | ||
| Dave Foutz | 33 | 1885 | ||
| Walter Johnson * | 33 | 1912 | ||
| Christy Mathewson * | 33 | 1904 | ||
| Jouett Meekin | 33 | 1894 | ||
| Tony Mullane | 33 | 1886 | ||
| Henry Porter | 33 | 1885 | ||
| Old Hoss Radbourn * | 33 | 1882 | ||
| Amos Rusie * | 33 | 1891 | ||
| Amos Rusie * | 33 | 1893 | ||
| Jack Stivetts | 33 | 1891 | ||
| Mickey Welch * | 33 | 1886 | ||
| Cy Young * | 33 | 1901 | ||
| 97 | Ice Box Chamberlain | 32 | 1889 | |
| Jesse Duryea | 32 | 1889 | ||
| Bob Emslie | 32 | 1884 | ||
| Tim Keefe * | 32 | 1885 | ||
| Silver King | 32 | 1887 | ||
| Kid Nichols * | 32 | 1894 | ||
| Lee Richmond | 32 | 1880 | ||
| Amos Rusie * | 32 | 1892 | ||
| Gus Weyhing | 32 | 1892 | ||
| Cy Young * | 32 | 1902 |