What Does a Backward K Mean in Baseball?

- September 5, 2023

Baseball’s box score has all kinds of shorthand, which came from a need to keep things concise, since box scores were only printed in newspapers for the first 100 years after box scores started being used. While baseball fans are familiar with other box score abbreviations such as HR for Home Run, E for Error, SB for Stolen Base and DP for Double Play, the backwards K and its origins remain somewhat of a mystery.

Nowadays, the letter K is often chanted by fans when an opposing player has 2 strikes, while some fans carry placards with the letter K inscribed on them to tally how many strike outs the home team’s pitcher has racked up.

But what does a backward K mean in baseball? The K stands for strikeout, and while other box score abbreviations are fairly obvious, why does “K” stand for a strikeout in baseball?

What Is a Strikeout and When Does It Happen?

A strikeout happens when a batter gets three strikes against him during a single time at-bat. In most circumstances, the batter is out after the third strike.  

What constitutes a strike? A pitch is declared a “ball” by the home plate umpire if the batter didn’t swing and the ball did not cross the plate within the legal strike zone. A foul ball with zero or one strike is ruled a strike. If a bunted ball with two strikes rolls foul, the batter strikes out. 

There are times when a strikeout doesn’t result in an out. One instance would be on the rare occasion that a swinging third strike results in a passed ball or wild pitch, and the batter reaches first safely. Statistically speaking, both the pitcher and batter record a strikeout. 

Usually, a strikeout indicates that a pitcher dominated the batter in an at-bat. However, today’s “swing for the fence” mentality of hitters results in overswinging and chasing bad pitches, resulting in a higher strikeout rate than in the past. Nevertheless, a strikeout is a strikeout. 

Why Is a K Used for a Strikeout in the Scorecard, and What Does a Backward K Indicate?

Origins of K for Strikeout

There are several oddities when it comes to symbols used when keeping a baseball scorecard. One of which is the use of the letter ‘K’ for a strikeout. A more logical choice would be ‘S’ since strikeout begins the letter ‘S.’ So why use ‘K’?

One reason that ‘S’ wasn’t chosen to represent a strikeout is that it was already used for a sacrifice, which was quite common in the early days of baseball.  

Therefore, Henry Chadwick, who invented the scorecard to keep track of the action of a baseball game, decided on the letter ‘K’ more than 150 years ago. The reasoning behind the decision is that the strikeout was commonly just called “struck,” and the last letter in struck is ‘K.’

Chadwick invented the box score two decades after Abner Doubleday invented baseball. Keeping score and records had been incredibly erratic those first 20 years due to the inconsistent nature of recording game action. The decision behind creating the box score was to keep fans tuned into how players did throughout the game. There was certainly no television or photography back in that era, so unless you were a fan in attendance, reading a box score was the only way to get a play-by-play breakdown. Chadwick’s innovative scoring system helped him make the Hall of Fame in 1938.

While ‘S’ was used for a sacrifice, most modern-day scorecards use ‘Sac’ for sacrifice or ‘SH’ for Sacrifice Hit and ‘SF’ for Sacrifice Fly. Many propose the use of ‘S’ for a single instead of the more common ‘1B’.

Meaning of the Backwards K

A statistic that has evolved over the years is the backward ‘K.’ In baseball; the backward ‘K’ means that a batter struck out looking. It doesn’t matter how the first strikes occurred, whether fouling off none, one, or two pitches. The only pitch that matters is the third strike.  

Frequent use of the backward K dates back to 35 years ago at Shea Stadium in New York. Whenever Dwight Gooden, a big strikeout pitcher in his early years in the league, was on the mound, fans in the stands would post all the strikeouts with a K or backward K.

Striking Out Looking – What Does It Mean to Strike Out Looking?

MLB Superstars Striking Out

How does striking out looking happen with regularity at the Major League level? Strike our looking can occur when a batter thinks the pitch is out of the strike zone, and in some cases, that is true, and the umpire missed the call. 

A more common reason is when a pitch completely fools the player. For example, a batter could be looking for a fastball and gets a nasty curveball that ‘locks’ the batter, and he freezes, unable to get the bat off his shoulder.

Another term used for a strikeout is a ‘punch out.’ Because of this, you would probably think that ‘PO’ would mean a strikeout, but this instead denotes a put-out or pop-out. Announcers around baseball regularly use the more flamboyant term ‘punch out’ rather than strike out, particularly in crucial stages of the game.

Understanding ‘K Rate’ Statistic

If you are a fan that probes beyond the basic statistics, you may have come across ‘K Rate.’ What exactly is K Rate? 

According to Major League Baseball, the’ K Rate’ is how often a pitcher records a strikeout. It’s simply a ratio between the number of strikeouts to the total batters faced. Another way to see how effective a pitcher is in striking out batters is to calculate the number of strikeouts per nine innings.

These numbers provide quick and easy methods for managers to see who the top strikeout pitchers are. This data is crucial when any contact could bring in a run, and the strikeout is desperately needed.

Generally, the higher a pitcher’s strikeout rate, the more effective he is at keeping runs off the board.

Most Strikeouts in an MLB Game by a Single Pitcher

With all this talk about ‘K’ and backward ‘K,’ you may be wondering what the most strikeouts are in a Major League Baseball game. The most are 20 in a nine-inning game, which has occurred on several occasions.

Roger Clemens (April 29, 1986, vs. Mariners, September 18, 1996, vs. Tigers)

In just his 40th Major League appearance, the 23-year-old dominated the Mariners, punching out 20 of the 30 batters he faced. He nearly pitched a shutout, allowing only one run on three hits with no walks.

Ten years later, Clemens was at it again. This time in the third-to-final start of his career in a Red Sox uniform. Not only did Clemens match the 20 strikeouts without a walk, but he also recorded a shutout against the Tigers.

Kerry Wood (May 6, 1998, vs. Astros)

Having been drafted just three years prior, Wood entered only his second month as a Major League pitcher. After a rocky start in which his ERA approached six, Wood faced a tough Astros’ lineup that features Jeff Bagwell and Craig Biggio.

Despite two future Hall of Famers in the line-up, Wood fanned 20 of the 29 batters he faced, allowing only one hit and no runs. Wood’s start was so dominating that his Game Score of 105 ranked the highest in league history for a single start.

Randy Johnson (May 8, 2001, vs. Cincinnati)

To see Johnson’s name on this list isn’t a surprise considering he racked up 4875 strikeouts in his career. 

Johnson fanned 20 of the 29 batters he faced, allowing only one run, one walk, and three hits. However, the Diamondbacks failed to score in the 9th, and Johnson was ejected from the game.

For the season, Johnson struck out the 3rd most batters in a season with 372.

Max Scherzer (May 11, 2016, vs. Tigers)

Pitching against his former team, Scherzer entered the ninth inning, having struck out 18. After giving up a leadoff home run to J.D. Martinez and letting the tying run reach base, Scherzer recorded his 20th strikeout with a chance to top the record.

James McCann grounded out, and the record remained at 20.

Steve Carlton (September 15, 1969, vs. Mets) – 19 strikeouts

One of only four pitchers in MLB history with 4000 or more strikeouts, Carlton came close to tying the mark, although he was never in a position to reach 20.

He entered the ninth inning with 16 punchouts and struck out the side to reach 19.

Tom Seaver (April 22, 1970, vs. Padres) – 19 strikeouts

Seaver, similar to Carlton, reached the 9th inning with 16 strikeouts. He fanned the side to end the game with 19. Seaver went on to become one of the top pitchers in the history of the game.

Nolan Ryan (August 12, 1974, vs. Red Sox) – 19 strikeouts

The all-time leader in strikeouts with 5714, Ryan’s resume also included seven-no hitters. His 19th strikeout came with two gone in the 9th inning. Rick Burleson flew out to prevent Ryan from reaching the 20 –strikeout plateau.

David Cone (October 6, 1991, vs. Phillies)

On his last start of the 1991 season, Cone had 19 strikeouts with one out to go. Dale Murphy grounded out to end the game, spoiling Cone’s chance at the 20th strikeout. Cone went on to win the Cy Young Award.


The backward K is visible in baseball stadiums around Major League Baseball. The fans use the symbol to remind everyone how many strikeouts a pitcher has during the game.

They are impossible to miss, seen as large banners with red or black lettering. The more backward K signs there are, the more you know that pitcher is really on his game, fooling opposing hitters.

The easy system used to record strikeouts has been used in baseball and worldwide for a century. The backward K is likely to remain as the symbol for striking out looking, and the K will be used to signify that a player has gone down swinging.

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