From BR Bullpen

Abbreviations K/BB
Type Pitching
Components strikeouts, walks

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.

The all-time major league record for the best K/bb ratio was set twice in a span of three seasons: first by Phil Hughes of the Minnesota Twins in 2014. In 209 2/3 innings, he struck out 186 batters and allowed only 16 walks, for a ratio of 11.63. Two years later, in 2016, in an injury-shortened season, Clayton Kershaw struck out 172 batters while walking only 11 opponents in 149 innings, for K/bb ratio of 15.64. However, Hughes can still be considered to hold the official mark as Kershaw did not achieve the minimum of 162 innings (one per game played by his team) which is usually considered the threshold for pitching records of this type. The previous mark had been set by Bret Saberhagen of the New York Mets in 1994: he struck out 143 and walked 13 for a ratio of 11.00. It should be noted that some relief pitchers may have had higher ratios in shorter stints.

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.