Justin Masterson struck out a career-high 10 batters against his former team Monday night, but even more impressive, Masterson needed just nine pitches to record three strikeouts against the Red Sox in the game's fourth inning.
Masterson's immaculate inning saw him strike out Jonny Gomes, Grady Sizemore and the recently returned Stephen Drew on nine straight pitches. The right-hander got four swings and misses in the inning and gave the Red Sox fits all night, allowing just seven batters to reach base over seven strong frames.
Masterson's dominant fourth was actually the third time a pitcher has thrown an immaculate inning in Major League Baseball this season. Cole Hamels threw an immaculate inning against the Reds on May 17 and Rays reliever Brad Boxberger also accomplished the feat on May 8. Prior to this season, Toronto's Steve Delabar last pitched an immaculate inning against the A's on July 30, 2013.
According to Baseball Almanac, the feat has happened 73 times in baseball history (and just 26 times in AL history) dating back to 1889. Since 2000, major league pitchers have thrown 24 different immaculate innings, which is far greater than the rate prior to the turn of the century.
The increased prevalence of the immaculate inning is yet more evidence that pitchers currently have the upper hand against their hitting counterparts. Major league batters are now striking out at a 20.4 percent rate, which would rank as the highest ever mark dating back to 1920.