K% Change

Due to popular demand and to decrease general confusion, K% has been changed from K/AB to K/PA.

On average, you’ll see players’ K% drop about 2% and, at the very most (rare cases like Adam Dunn), about 6%.

This is a site-wide change and impacts stats pages, splits, leaderboards, and graphs that contain K%.

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David Appelman is the creator of FanGraphs.

43 Responses to “K% Change”

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  1. Telo says:

    Great, thanks. On a related note – are there plans for K/PA and BB/PA to be added for pitchers, in addition to the per 9 rates?

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  2. RMR says:

    Excellent! It may not have been a big change numerically, but the logical consistency is important.

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  3. PWH says:

    You’re the man, David Appelman.

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  4. Kyle says:

    dumb question… what’s the difference between At bats and plate appearances?

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    • anon says:

      PA = AB + BB + HBP + sacrifices

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    • balagast says:

      BB’s, HBP etc don’t count as an AB but they do count as a PA.

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    • Telo says:

      You have come to the right place to learn about baseball, but for the basics, these links will help:



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      • Person says:

        Wow, that article on plate appearances is a cluster-you-know-what. A plate appearance is exactly what it sounds like. Perhaps they could call it a CPA (completed plate appearance); takes care of what should be the only source of confusion. It’s at bats that is needlessly complex a stat… but I’ll let Joe Posnanski finish the thought:

        “Subtract the walks. No, seriously, just subtract those. We don’t care about those.

        “Now, subtract the hit-by-pitches. Get rid of them.

        “Now, subtract the times that the player hit a fly ball that allowed a runner to tag up and score from third base.

        “Now, subtract the times the batter bunted a runner from first to second base, or second to third, or third to home but still made an out. Do not subtract the plate appearance if the batter successfully made it to first base. Do not subtract it if he hit a hard smash that accomplished PRECISELY THE SAME THING as a bunt. Do not subtract it if he hit a check-swing dribbler that was KIND OF like a bunt but did not seem from the press box to be a purposeful bunt.

        “Remember to include the times he reached base but only because of a defensive blunder.

        “OK, you have that number? We call those ‘at-bats.'”

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      • joser says:

        I guess this would make a great example of creeping complexity. It totally made sense to leave BBs out (don’t want to punish a player’s batting average because he’s good at taking walks), and then they just kept piling on “refinements” until we got to the current definition.

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      • Yirmiyahu says:

        and catcher interference disappears into the ether, never to be included anywhere.

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  5. Polyrhythm07 says:


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  6. Drew says:

    I based all of my fantasy lineups on the previous values.

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  7. Jack says:

    Great, thanks!

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  8. Phils Goodman says:


    Completely unrelated, but could you add something like a League Average ‘player page’? Meaning that it would have the same layout as a player page, but all the entries would be for league average in the applicable stat columns. That’s the easiest way I can think of to add a tool to help provide context for stats that are not adjusted for league average and to evaluate player splits and against league average splits.

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    • Telo says:

      Interesting, though it’d probably more useful to expand the current league average buttons to all other tabs, not just plate discipline etc.

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    • joser says:

      It’s an interesting idea (I’d enjoy looking at that page) but it has a problem: the average changes every year, and you want to be able to look at all (or any one) of them. So we’d end up with a huge family of players named “Player” all sharing the middle name “Average” but each with a different year as a first name.

      Not to mention the next step would be to add average teams to the team pages (probably three: NL, AL, and MLB… again, for each year).

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      • phoenix2042 says:

        nope. you just have average player and update with each year like a real player page. it would track year to year changes just like any players stats year to year… treat it like a real player.

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      • Barkey Walker says:

        Many players play for more then one year, so the page can take that into account. To keep it from getting huge, you could do it by decade.

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  9. MikeS says:

    Thanks for making Adam Dunn slightly less bad.

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    • Trotter76 says:

      I meant to hit thumbs up but hit thumbs down by mistake. I’d like the record to show that I liked MikeS’ comment.

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  10. Mom says:

    David honey I am very proud of you today.

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  11. Ah, fantastic. I’ve been waiting for this for a while, and I’m really happy to finally see its implementation. Looking forward to seeing K/PA and BB/PA numbers for pitchers, too. Awesome stuff.

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  12. theeiffeltower says:

    You can get BB/PA and K/PA for this year and the last couple years at firstinning.com

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  13. RC says:

    Now, if only we could get the same thing done to FIP.

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  14. dcs says:

    The next order of business should be taking out the intentional walks from stats like BB%, or BB/K. Call them NBB, for non-intentional walks. I can’t think of any sort of evaluation or analysis that wouldn’t be made easier for the user. Just because baseball made a mistake in not having NBB as an official stat doesn’t mean that Fangraphs has to keep perpetuating that.

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  15. Vlad says:

    Bah, humbug.

    K/AB is a more useful indicator of trouble ahead for minor league hitters than K/PA.

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  16. hank says:

    Any thoughts on using K% or BB% instead of K/9 or BB/9 for pitchers?

    I know per 9 is familiar to folks but BABIP fluctuations can make comparisons at times tricky when looking at year to year increases or decreases (or comparing players to each other)

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  17. John says:

    How is K/AB more indicative of future success for a minor leaguer than K/PA? Theoretically I get why you might want to exclude BBs but practically you want to know how many times player X K’s per time he walks up to the plate. Also, if a player increases his BB’s from one year to the next (w/K’s constant) doesn’t his K/AB automatically increase as well(where as his K/PA doesn’t)?

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  18. Feeding the Abscess says:

    Sweet, now Barry Bonds’ 2004 season has gone from simply obscene to absolutely retarded. 37.6% BB, 6.6% K, as opposed to a mark previously around 11% K.

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  19. Matty Brown says:

    How about a statistic for 3-pitch walks allowed? (although that may only apply to the Mariners)

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  20. Adam Dunn says:

    Thanks, David! I needed all the help I could get this year

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