Strikeouts per nine innings pitched

The all-time Major League Baseball (MLB) career leader (minimum of 1,000 innings pitched) in this statistic through 2024 is Blake Snell (11.23).

The only other pitchers who had averaged over 10 K/9 are: Chris Sale (11.09), Robbie Ray (11.07), Jacob deGrom (10.97), Max Scherzer (10.65), Randy Johnson (10.61), Yu Darvish (10.59), Stephen Strasburg (10.55), Gerrit Cole (10.37), Kerry Wood (10.32), and Pedro Martinez (10.04).

[2] The career leader in K/9 among MLB relievers (minimum of either 300 innings pitched or 200 appearances) through 2020 was Aroldis Chapman (14.88), followed by Craig Kimbrel (14.66), Kenley Jansen (13.25), Rob Dibble (12.17), David Robertson (11.93), and Billy Wagner (11.92).

[3][4][5] In 2022, Kyle Harrison led Minor League Baseball with 14.8 strikeouts per 9 innings, the highest rate for a pitcher in the minor leagues in a season (minimum of 100 innings pitched) dating back to 1960.

[6][7] One effect of K/9 is that it may reward or "inflate" the numbers for pitchers with high batting averages on balls in play (BABIP).