For single seasons, From 1901 to 2008, (requiring W=20 and L=9), sorted by most recent date

  Cnt Player            Year  W  L Age Tm  Lg  G   GS CG SHO GF  W-L% SV   IP   H   R   ER  BB  SO   ERA  ERA  HR  BF   AB  2B 3B IBB HBP  SH  SF GDP  SB CS Pk BK WP   BA   OBP   SLG   OPS  OPS   Pit  Str
 ----+-----------------+----+--+--+---+---+--+---+---+--+---+--+-----+--+-----+---+---+---+---+---+------+----+--+----+----+--+--+---+---+---+---+---+---+--+--+--+--+-----+-----+-----+-----+----+----+---- 
    1 Mike Mussina      2008 20  9  39 NYY AL  34  34  0   0  0  .690  0 200.1 214  85  75  31 150   3.37  128 17  819  769 47  2   3   8   4   7  24  12  7  0  0  4  .278  .310  .411  .721   90 3121 2079 
    2 Darryl Kile       2000 20  9  31 STL NL  34  34  5   1  0  .690  0 232.1 215 109 101  58 192   3.91  120 33  960  870 50  4   1  13  11   8  16   2 11  0  1  8  .247  .301  .428  .729   85 3502 2284 
    3 Bill Gullickson   1991 20  9  32 DET AL  35  35  4   0  0  .690  0 226.1 256 109  98  44  91   3.90  107 22  954  890 51  7  13   4   8   8  22  15  8  1  0  4  .288  .321  .435  .756  105           
    4 Roger Clemens     1987 20  9  24 BOS AL  36  36 18   7  0  .690  0 281.2 248 100  93  83 256   2.97  154 19 1157 1055 52  5   4   9   6   4  14  26 14  1  3  4  .235  .295  .348  .643   68           
    5 Mike Krukow       1986 20  9  34 SFG NL  34  34 10   2  0  .690  0 245   204  90  83  55 178   3.05  116 24  987  913 36  6   4   4  10   5  13  23  7  0  0  4  .223  .269  .355  .624   80           
    6 Tom Browning      1985 20  9  25 CIN NL  38  38  6   4  0  .690  0 261.1 242 111 103  73 155   3.55  107 29 1083  987 48  1   8   3  13   7  18  16  8  1  0  2  .245  .297  .384  .681   92           
    7 Ed Figueroa       1978 20  9  29 NYY AL  35  35 12   2  0  .690  0 253   233  96  84  77  92   2.99  121 22 1038  939 44  4   4   3  13   6  21  18 10  6  1  6  .248  .305  .374  .679   92           
    8 Mike Torrez       1975 20  9  28 BAL AL  36  36 16   2  0  .690  0 270.2 238 103  92 133 119   3.06  115 15 1144  994 36  4   5   5   7   5  35   9 12  2  1 10  .239  .331  .329  .660   92           
    9 Vida Blue         1973 20  9  23 OAK AL  37  37 13   4  0  .690  0 263.2 214 108  96 105 158   3.28  108 26 1083  956 29  6   2   4   8  10  28  14  7  2  2 15  .224  .300  .348  .648   86           
   10 Jim Palmer        1971 20  9  25 BAL AL  37  37 20   3  0  .690  0 282   231  94  84 106 184   2.68  125 19 1165 1044 37  4   6   4   6   5  14  17 11  1  2  8  .221  .294  .319  .613   81           
   11 Al Downing        1971 20  9  30 LAD NL  37  36 12   5  0  .690  0 262.1 245  93  78  84 136   2.68  121 16 1095  992 33  1   3   3  12   4  26  11  4  1  1 12  .247  .307  .331  .638   91           
   12 Mike Cuellar      1971 20  9  34 BAL AL  38  38 21   4  0  .690  0 292.1 250 111 100  78 124   3.08  109 30 1166 1068 33  3   1   1  13   6  27  12 16  6  0  3  .234  .285  .355  .640   87           
   13 Joe Coleman       1971 20  9  24 DET AL  39  38 16   3  0  .690  0 286   241 106 100  96 236   3.15  116 17 1174 1051 38  4   3   7  13   7  22  16 10  0  1  7  .229  .296  .322  .618   77           
   14 Steve Carlton     1971 20  9  26 STL NL  37  36 18   4  0  .690  0 273.1 275 120 108  98 172   3.56  101 23 1171 1050 37  7  11   5  10   8  19   9  9  8  0 12  .262  .326  .376  .702  101           
   15 Mel Stottlemyre   1965 20  9  23 NYY AL  37  37 18   4  0  .690  0 291   250  99  85  88 155   2.63  129 18 1188 1073 44 10   3   7  15   5  29  12 11  1  0  5  .233  .294  .343  .637   87           
   16 Jim Maloney       1965 20  9  25 CIN NL  33  33 14   5  0  .690  0 255.1 189  77  72 110 244   2.54  148 13 1048  917 30  4   3   5  13   3  19  24  7  0  0 19  .206  .294  .290  .584   66           
   17 Dean Chance       1964 20  9  23 LAA AL  46  35 15  11  7  .690  4 278.1 194  56  51  86 207   1.65  198  7 1093  994 20  4   9   2   9   2  31   8  4  0  0  9  .195  .260  .244  .504   53           
   18 Ray Herbert       1962 20  9  32 CHW AL  35  35 12   2  0  .690  0 236.2 228  90  86  74 115   3.27  120 13  984  896 41  7   4   1   7   6  27   4  2  1  0  4  .254  .310  .359  .669   86           
   19 Vern Law          1960 20  9  30 PIT NL  35  35 18   3  0  .690  0 271.2 266 104  93  40 120   3.08  122 25 1091 1036 38  9   8   4   7   4  33   5  6  0  1  2  .257  .286  .383  .669   84           
   20 Early Wynn        1956 20  9  36 CLE AL  38  35 18   4  2  .690  2 277.2 233  93  84  91 158   2.72  154 19 1144 1022 37  2   7   5  12  12  20   4  4  0  0  5  .228  .291  .324  .615   65           
   21 Herb Score        1956 20  9  23 CLE AL  35  33 16   5  1  .690  0 249.1 162  82  70 129 263   2.53  166 18 1022  880 30  0   2   2  13   7  17   7  4  0  0 11  .184  .288  .280  .568   53           
   22 Billy Pierce      1956 20  9  29 CHW AL  35  33 21   1  2  .690  1 276.1 261 108 102 100 192   3.32  124 24 1166 1046 39  8   7   3  13   1  18   3  8  0  1  6  .250  .317  .371  .688   84           
   23 Harvey Haddix     1953 20  9  27 STL NL  36  33 19   6  2  .690  1 253   220  97  86  69 163   3.06  139 24 1031                  4                        0  9                            0           
   24 Don Newcombe      1951 20  9  25 BRO NL  40  36 18   3  2  .690  0 272   235 115  99  91 164   3.28  120 19 1125                  6                        0  7                            0           
   25 Howie Pollet      1949 20  9  28 STL NL  39  28 17   5  7  .690  1 230.2 228  80  71  59 108   2.77  150  9  964                  2                        0  2                            0           
 ----+-----------------+----+--+--+---+---+--+---+---+--+---+--+-----+--+-----+---+---+---+---+---+------+----+--+----+----+--+--+---+---+---+---+---+---+--+--+--+--+-----+-----+-----+-----+----+----+---- 
  Cnt Player            Year  W  L Age Tm  Lg  G   GS CG SHO GF  W-L% SV   IP   H   R   ER  BB  SO   ERA  ERA  HR  BF   AB  2B 3B IBB HBP  SH  SF GDP  SB CS Pk BK WP   BA   OBP   SLG   OPS  OPS   Pit  Str
 ----+-----------------+----+--+--+---+---+--+---+---+--+---+--+-----+--+-----+---+---+---+---+---+------+----+--+----+----+--+--+---+---+---+---+---+---+--+--+--+--+-----+-----+-----+-----+----+----+---- 
   26 Cliff Melton      1937 20  9  25 NYG NL  46  27 14   2 14  .690  7 248   216  90  72  55 142   2.61  148  9 1004                  6                        0  2                            0           
   27 Pat Malone        1930 20  9  27 CHC NL  45  35 22   1  8  .690  4 271.2 290 145 119  96 142   3.94  124 14 1197                  6                        1  4                            0           
   28 Freddie Fitzsimmo 1928 20  9  26 NYG NL  40  32 16   1  7  .690  1 261.1 264 119 107  65  67   3.68  106 13 1084                  4                        0  6                            0           
   29 Lee Meadows       1926 20  9  31 PIT NL  36  31 15   1  1  .690  0 226.2 254 125 100  52  54   3.97   99 10  967                  4                        0  3                            0           
   30 Carl Mays         1924 20  9  32 CIN NL  37  27 15   2 10  .690  0 226   238  97  79  36  63   3.15  120  3  940                  4                        0  1                            0           
   31 Hugh Bedient      1912 20  9  22 BOS AL  41  28 19   0 11  .690  2 231   206  93  75  55 122   2.92  116  6  917                  3                        2  2                            0           
   32 Bob Wicker        1903 20  9  25 TOT NL  33  27 24   1  6  .690  1 252   240 115  83  77 113   2.96  106  3 1034                  3                        0  8                            0           
   33 Deacon Phillippe  1902 20  9  30 PIT NL  31  30 29   5  1  .690  0 272   265  90  62  26 122   2.05  134  1 1102                  4                        0  4                            0           

Seasons/Careers found: 33.

 Photos from the George Grantham Bain Collection at the Library of Congress.