Aroldis Chapman Doing Crazy Strikeout Things

Aroldis Chapman is hot. His fastball tops 100 mph. His slider is nearly unhittable. And he’s on the verge of breaking two strikeout records.

In 47.2 innings pitched through Wednesday, the Reds closer has racked up 16.99 strikeouts per nine innings, the highest in the majors this season for pitchers with at least 30 innings under their belt. In July, in 11.1 innings pitched, his strikeouts per nine innings has jumped to 20.65.

But it’s not just the number of strikeouts he’s recorded. It’s the lethal efficiency with which he’s dispensed with his adversaries. Chapman has struck out nearly half the batters he’s faced this season, posting a 49.7 strikeout rate through Wednesday. He’s faced 181 batters. He’s struck out 90 of them. In July alone, Chapman’s strikeout rate is at 65%. Forty batters faced. Twenty-six strikeouts. Oh, and he has a negative FIP for July.

Look at those numbers again and let them sink in. Almost unfathomable.

Since 2002 — the first season for which monthly splits are available — only one qualified reliever recorded a monthly K/9 higher than Chapman’s current 20.65 K/9 in July. Dodgers closer Kenley Jansen had a 21.07 K/9 in September, 2011.

Other than Jansen, only three qualified relievers have posted a K/9 of 18.00 or higher in any month from April 2002 to the present: Rafael Betancourt in August, 2010; Takashi Saito in June, 2008; and Darren Dreifort, in June, 2004. Since 2002, no qualified reliever has posted a monthly strikeout rate of 65%. The highest is Jansen’s 61.5% in September, 2011.

If Chapman maintains his season-long pace, he will establish new records for K/9 and K% for qualified pitchers dating back to 1918. The K/9 record was set just last year by Jansen. In 53.2 innings pitched, Jansen recorded 16.10 strikeouts per nine innings. This season Chapman is striking out almost one additional batter per nine innings. The K rate record is held by Eric Gagne, who struck out 44.8% of batters he faced in 2003, the year he won the National League Cy Young Award. Chapman’s currently at 49.7%. To be fair, Craig Kimbrel of the Braves is also ahead of Gagne’s 2003 pace so far this season. His K rate is at 45.8% in 39 innings pitched through Wednesday.

The key to Chapman’s strikeout madness is a fastball that averages 97.8 mph but runs as high as 102.4 mph and a slider that averages 88 mph and tops out at 91.7. He also throws a changeup, but rarely. Indeed, about 80% of Chapman’s pitches are fastballs. With that kind of velocity, his pitch mix isn’t terribly surprising.

And what happens when Chapman throws his fastball? Batters know it’s coming and, for the most part, they still can’t do much about it. It looks like this:

Chapman’s swinging strike rate on his fastball is 18.7%, the highest in the majors so far this season. Glen Perkins of the Twins is next, with a 17.4% swinging strike rate on his fastball. Joel Peralta of the Rays follows Perkins, at 16.9%.

For a secondary pitch, Chapman’s slider is nasty and effective. It looks like this.

The swinging strike rate on his slider is 22.3%. That doesn’t lead the majors but it’s pretty close. Boone Logan of the Yankees has posted a 23.9% swinging strike rate on his slider so far this season. Sergio Romo of the Giants is at 23.7% on his slider. But neither Logan nor Romo has a fastball anywhere near as effective as Chapman.

Aroldis Chapman is dominating batters and making them look silly. His strikeout numbers in July are off the charts. So too are his season-long numbers so far. If he keeps up this pace, he will shatter the record for highest K/9 and strikeout rate in a season. It’s amazing, and it’s very fun to watch.

Many thanks to Carson Cistulli for creating the .gifs for this post.

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Wendy writes about sports and the business of sports. She's been published most recently by Vice Sports, Deadspin and You can find her work at and follow her on Twitter @hangingsliders.

27 Responses to “Aroldis Chapman Doing Crazy Strikeout Things”

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  1. DJG says:

    What’s the IP requirement to be a qualified reliever?

    Ernesto Frieri is also doing crazy things (though not as crazy). He’s actually a little better than Kimbrel right now.

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    • DJG says:

      Frieri is better than Kimbrel in terms of K/9, I should clarify.

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    • TKDC says:
      FanGraphs Supporting Member

      Frieri has 2 more IP than Kimbrel. I’m sure he qualifies. But neither Kimbrel’s 15.00 or Frieri’s 15.15 is that high up the single season leaderboard.

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      • DJG says:

        I was just wondering in general what the qualification requirements are.

        My comment about Frieri was separate. I just noticed that he too was getting into some rarefied strikeout air.

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  2. DK says:

    It’s a good time to be a Reds fan. We have the pitcher with the fastest pitch, and the runner with the fastest legs coming up.

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  3. reds fan says:

    i guess chapman will never be a starter?

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    • Nick says:

      I’m starting to be okay with that. If memory serves, his velocity dropped significantly when he (briefly) was starting, and his results were not good. Sure, it would be better to get 200 quality innings a year from him, but he so far hasn’t shown that he can do that.

      On the other hand, Dusty is still talking about his future in the rotation, so we may yet get to find out if he can take the extra workload and slower fastball.

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  4. saucypony says:

    Glen Perkins has a 17.4% swinging strike rate on his fastball??

    What in the hell is he doing differently (other than just moving to the bullpen)? Last year it sat at 10.1%, 8.7% the year before that, and just 2.9% in 2009. The movement on his fastball has decreased every year since ’09, as well. Something is amiss here!

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  5. Phantom Stranger says:

    It’s insane someone of Chapman’s talent is being marginalized as a closer. It’s obvious he would be a very effective starter and the Reds are not fully exploiting his potential.

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    • Oliver says:

      Maybe. See Bard, Daniel for an example of what can go wrong though.

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    • SirBuckeye says:

      It’s also obvious that you don’t follow the Reds too closely. Chapman was the Reds best starter in spring training. He was awesome. Then Ryan Madsen got hurt. Then Bill Bray got hurt. Then Nick Masset got hurt. The Reds had six quality starters and a gaping wound in their bullpen so they reluctantly sent Chapman to pen. Most people thought he would only stay there until one of the starters struggled or got hurt. Well, low and behold, all five starters have been healthy and excellent all season for the Reds while Chapman has moved into the closer role. The Reds are in first place and are rolling right now even without their best player. Life is good for Reds fans. Chapman will get his shot at the rotation again next year.

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    • Snarf says:

      “marginalized as a closer”???

      Ask any Yanks fan in the last 12 years, having a closer is crucial. Mariano couldn’t hack it as a starter but is pretty lethal as a closer.

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      • Pitnick says:

        “Couldn’t hack it” is the key. If Rivera could have pitched anywhere near as well as a starter and stayed healthy enough to pitch 180 innings a year, he obviously would have been more valuable. Chapman didn’t get a chance to fail as a starter.

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      • Baltar says:

        Yes, when I want to get the best possible answer to a baseball question, I always ask a Yanks fan. Every single one of them knows more about baseball than anybody else.

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  6. Matty Brown says:

    People need to stop assuming elite relievers can throw 200 innings of even average baseball. Chapman is very valuable as a fireman. He should be able to produce ~3 War as a fireman.

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    • BlackOps says:

      Chapman’s not just an elite reliever; he’s having one of the best seasons a reliever has ever had. Not only is he more than an “elite” reliever, but he’s left handed. He needs a chance to fail as a starter.

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  7. tigermojo says:

    In 5.1 innings vs. the AL he has given up 7 earned runs. That means in his remaining 42.1 innings against the NL he has given up ONE!!! earned run against the Pirates.

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  8. B N says:

    “Since 2002 — the first season for which monthly splits are available”

    I assume you mean on this site? As certainly, K’s and PA’s have definitely been recorded so that monthly splits are eminently possible…

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  9. Keith says:

    Terrific piece. In general, might there be a statistical grain of salt that can be applied to the recent K rate explosion? I wasn’t surprised to see that, in 1927, Babe Ruth K’ed more than any other AL batter. The number surprised me. 89. (And Hack Wilson led the NL with 70.) As recently as 1993, Reggie Sanders led the AL with 114. Today, if you K just 114 times, you are the next Tony Gwynn. So I’d be interested in seeing K/9s over time. Alternatively I’d be interested to know why it’s irrelevant, that the rise is simply a result of pitchers throwing harder, for instance.

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    • Fatbot says:

      K% has indeed risen every year since 2008 and is at an all-time high of 19.7% and going higher. Here it is over time:,ss&rost=0&age=0&players=0&sort=9,d

      Yes an argument for why is these sorts of specialized relievers are just too good now. But I think it is obvious that a huge reason for these abberrations is hitters just don’t care about contact. (see Mark Reynolds famous response to his # of K, “who cares?”). They came up in the steroid era, the only way you move on to the next level is HR.

      Just look at each of the videos above. Look at both hitters’ 2-strike approach. Where are there eyes? Their heads? On the ball or swinging out of their shoes pulling their heads out? So awful it would make a little league coach blush.

      Chapman is awesome and would have great numbers no matter what. But clearly the numbers are being padded by just horrid hitting approaches. See also the fact that after generations of knuckleballers establishing a consistent baseline result to that pitch, Dickey seems like the best ever. You can either accept that, or the more likely reason that hitters are just not good at making contact which is spotlighted when facing special outliers like a 100 mph fastball or a knuckleball.

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    • gweedoh565 says:


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  10. Marc says:

    Boone Logan and Sergio Romo are also specialty relievers.

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  11. Colin P says:

    Not only is his fastball around 100 but part of the reason it’s so devastating is he releases it closer to plate than most guys. There was a cool sports science video about how he uses torque to generate velocity but also releases way out front to give the batter less time to react

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