From BR Bullpen
In baseball statistics, strikeout-to-walk ratio (K/BB) is a measure of a pitcher's ability to control pitches; calculated as: strikeouts divided by bases on balls. A pitcher that possesses a great K/BB ratio is usually a dominant power pitcher, such as Randy Johnson, Pedro Martínez, Curt Schilling, or Nolan Ryan. However, in 2005, Minnesota Twins starting pitcher Carlos Silva easily led the major leagues in K/BB ratio with 7.89:1, despite only striking out 71 batters over 188⅓ innings pitched; he walked only 9 batters.
A hit by pitch is not counted statistically as a walk and therefore not counted in the strikeout-to-walk ratio. At youth levels where hit by pitches are more common, including hit by pitches may be a more useful statistic. Walks plus hits per inning pitched can also be used to compare pitchers.