By striking out 12 St. Louis Cardinals hitters on Tuesday night, Chris Sale of the Chicago White Sox tied Pedro Martinez’s record for striking out at least ten hitters in eight games in a row. The feat is an impressive one, requiring a consistent level of performance for more than a month. Only four pitchers have had such a streak last more than five games, per Baseball Reference’s Play Index (Much of the data throughout this piece comes the Play Index).

Year Games IP BB ERA SO Chris Sale 2015 8 60 9 1.80 97 Pedro Martinez 1999 8 62 8 1.16 107 Randy Johnson 2001 7 56 13 1.93 90 Pedro Martinez 1999 7 53.2 13 1.51 84 Nolan Ryan 1977 7 60 45 2.55 90 Randy Johnson 2002 6 50 14 1.08 79 Randy Johnson 2000 6 45.1 11 1.99 71 Randy Johnson 1999 6 49 11 1.84 65 Randy Johnson 1998 6 51 10 2.29 74 Pedro Martinez 1997 6 50.2 15 1.78 72 Nolan Ryan 1972 6 54 25 1.33 76

During the streak, Sale has an ERA of 1.80 and a 1.27 FIP while striking out 42.5% of hitters. Counting only strikeouts during the streak, Sale’s 97 Ks would be tied for ninth with Sonny Gray for strikeouts for the entire season in the American League. WIthin Sale’s current streak is a five-game span where Sale struck out at least 12 hitters every game which is also tied with Pedro Martinez (as well as Randy Johnson) for the longest streak in history. As it stands, Sale’s 141 strikeouts and 35% K-rate are number one in baseball. Although unlikely, Sale has an outside shot at becoming the first pitcher to achieve 300 strikeouts since 2002 when both Randy Johnson and Curt Schilling achieved that mark for the Arizona Diamondbacks.

While Sale’s streak is impressive, all of the pitchers listed on the leaderboard above played in the last two decades except for Nolan Ryan. Achieving high numbers in strikeouts looks to be easier of late compared to prior generations with strikeout rates fluctuating over time. Here are the numbers for strikeout rates for starters over the last century.

Strikeout rates reached a peak in the 1960s before dropping for several decades. They would not get back up to those levels until the mid-90s before reaching around 19% over the last few years. While strikeout rates have gone up, that does not necessarily mean that getting a ten-strikeout game is easier as starters have pitched fewer innings per game due to an increased emphasis on the bullpen. Despite the emphasis on the bullpen the number of double-digit strikeout games per season has risen dramatically over the last few years. The graph below shows the number of ten-strikeout games in every year over the last century.

Much like strikeouts in general, the number of ten-strikeout games was high in the 60s before the mound was lowered and the designated hitter was implemented. Last season, there were 209 double-digit strikeout games, more than double the number from 2005 and this season there have already been 105 ten-strikeout performances. When comparing eras, strictly using the numbers is misrepresentative as expansion and a 162-game schedule have increased the number of games overall and provided more chances for 10-K games. In 1963, there were only 136 starts with 10 strikeouts, but at 4.2% of starts, that number is roughly equivalent to last season’s 4.3% of starts with 10-K games.

The graph below includes the percentage of starts where the starter reached double-digit strikeouts. To provide some context for eras and potentially provide a different baseline from comparison, the percentage of nine-strikeout games and eight-strikeout games are also included.

As the graph shows, there are a lot of years where a nine-strikeout game or an eight-strikeout game would be just as likely as a ten-strikeout game in today’s era. If you attend every game of a three-game series in 2015, you are more likely than not to see a nine-strikeout performance. Pedro Martinez’s streak that Chris Sale just tied is more impressive given the environment. The percentage of ten-strikeout games is 4.5% compared to just 2.7% in 1999 when Martinez achieved his streak. Martinez’s already incredible streak is made even more amazing considering that Martinez achieved at least 11 strikeouts in every game during his streak, a feat seen in just 1.4% of starts that year. No player has ever had a similar streak higher than six games.

Attempting to adjust for era based on the frequency of the high strikeout games, we can find a few more streaks similar to Sale’s this season. Pre-1945, the frequency of high strikeout games was so low, there was only one eight-game streak of even six strikeouts. In 1924, Dazzy Vance struck out at least six players in eight straight starts. As a rarity, the streak is impressive, but six-strikeout games occurred 5.5% of the time in 1924, making the streak not quite as unlikely as Sale’s streak this season.

Since 1945, there have been 29 eight-game streaks of at least eight strikeouts, topped by Randy Johnson’s 17-game streak spanning over the 1999 and 2000 seasons. Nolan Ryan has had multiple eight-game, eight strikeout streaks and Bob Gibson and Sandy Koufax had one each as well, but the rate of eight-strikeout games has been above five percent in every year since 1955, making those streaks dissimilar from Sale’s current run. In 1946, Bob Feller had a nine-game streak when the incidence of eight-strikeout games was 4.9%, similar to the 4.5% 10-K rate of this season.

There have only been ten eight-game streaks of at least nine strikeouts in last century. In 1987, Roger Clemens had an eight-game streak when the rate of 9-K games was 5.2%, and in 1994 Randy Johnson had an eight-game streak when the rate was 4.9%. Pedro Martinez’s record streak occurred when the rate of nine-strikeout games was 4.5%, and he actually had another streak that season, this one of nine games of at least nine strikeouts. 1992 David Cone pulled off an eight-game streak when the rate was at just 3.8%, and Dwight Gooden pulled off a nine-game streak in 1984 when the rate was just 3.9%. Nolan Ryan has the longest streak of 9-K games with 11 in 1977 when the rate of 9-K games was just 4.1% that season.

The list of players with streaks of at least eight games when the rate of x-strikeout games was under 5% is below.

Year Games Minimum Ks Rate of (8-11)-K games Bob Feller 1946 9 8 4.9% Nolan Ryan 1977 11 9 4.1% Dwight Gooden 1984 9 9 3.9% David Cone 1992 8 9 3.8% Randy Johnson 1994 8 9 4.9% Pedro Martinez 1999 9 9 4.5% Pedro Martinez 1999 8 11 1.4% Chris Sale 2015 8 10 4.5%

Pedro Martinez is amazing, but Chris Sale’s streak is rare regardless of era. Strikeouts have been on the rise, but Sale’s streak puts him in some great company. Short, in-season streaks might be somewhat arbitrary, but Chris Sale has been on a run rarely seen in baseball’s long history.