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Danny Duffy lives in the danger zone

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Why the Royals’ young starter could have more staying power than other ballyhooed breakout aces

MLB: Kansas City Royals at Detroit Tigers Rick Osentoski-USA TODAY Sports

The art of throwing pitches down the heart of the plate, middle-middle, doesn’t sound like it should be an art at all. Not unless you also consider spilling your coffee to be an art form, or tripping up the stairs. It sounds insane.

That makes this list interesting. The pitchers who threw the most pitches down the middle happened to be some of the league’s best pitchers.

Name Middle-middle pitches Total pitches Percentage AVG SLG
Stephen Strasburg 183 2385 7.67 0.317 0.400
Rich Hill 138 1811 7.62 0.326 0.435
Clayton Kershaw 153 2062 7.42 0.259 0.407
Max Scherzer 255 3563 7.16 0.231 0.513
Danny Duffy 190 2707 7.02 0.299 0.584
Chris Sale 240 3431 7 0.270 0.432
Mike Foltynewicz 148 2120 6.98 0.314 0.451
Carlos Martinez 209 3027 6.9 0.341 0.538
Matt Boyd 114 1683 6.77 0.341 0.683
Jordan Zimmermann 115 1706 6.74 0.317 0.634
Yu Darvish 106 1579 6.71 0.211 0.395


Sorry to disappoint, but this is not moving toward the conclusion that throwing pitches down the pipe is a recipe for success. Instead, we are going to ask whether a willingness to pitch there, or thereabouts, might be an indicator of other attributes – bat-missing ability chief among them – that portend success.


Confidence was not always something we could associate with Danny Duffy. His path to the Majors was a rocky one, and his progression once there was perhaps equally arduous. Despite performing admirably during the Royals’ World Series runs, Duffy himself told Royals coaches and front office personnel he preferred to remain in the bullpen coming into spring 2016.

And then changes happened – any one of which might be worth its own examination. But suffice it to say, by July 27, an evening on which Duffy started against the Angels, he was functioning as the Royals’ ace. In the first inning, the task before him was Mike Trout.

Duffy alternated a ball and a strike before using his slide step to zip a fastball past a swinging Trout for strike two. The Royals broadcast called the inside heater “a challenge pitch.” With the next pitch, Duffy did what most pitchers blessed with heat would do – fired an eye-level fastball to try and steal a swing. It was Mike Trout, though, and thus it didn’t work.

The next pitch was the interesting one. It was just 2-2. What’s your move against the best player in the world? Maybe try another tactic to get Trout to chase and increase your likelihood of a miss or weak contact? You’d think. But Duffy fired one right down Main Street, and Trout swung. His head locked onto the pitch like it had so many times before. Then his bat crossed below the ball, which whizzed into Salvador Perez’s glove at 95 mph.

Trout gave a quick, confused twitch of his head as Duffy left the mound.

The next time out, Duffy hurled a masterpiece against the Rays – setting the PITCH f/x era record for swinging strikes in a game.


MLB: St. Louis Cardinals at Houston Astros Troy Taormina-USA TODAY Sports

We have recently witnessed several pitching performances that, in conjunction with some new technology and data, have broadened our understanding of how outs can be created. Jake Arrieta induced so much “soft contact” that we had to give him credit. Dallas Keuchel broke the bottom of the strike zone. Zack Greinke and Kyle Hendricks showed us that for hitters, there is a darkness on the edge of the plate.

Compared to those dominant seasons, Duffy’s 2016 breakout looks … not that impressive! But pitching, that most complicated of crafts, tends to throw us off the scent of answers. Despite displaying a capacity for dominance, there are pretty good reasons to doubt, say, Keuchel’s ability to succeed in a world where the lower boundary of the strike zone is higher, and where hitters are thinking about, and planning for, the 2015 AL Cy Young winner instead of a dude on the Astros with a beard.

Which is where Duffy’s 2016 begins to distinguish itself. He ranked fourth among pitchers with 120+ Major League innings in zone-contact rate, which measures exactly what you think it measures. Personally, I like to think of it as the Stuff Stat. His 81.3 percent trailed only Clayton Kershaw, Max Scherzer, and the knuckleballer Steven Wright. Opposing hitters made contact on Andrew Miller strikes more often.

Duffy also ranked third in zone percentage, behind only Kershaw and Steven Matz – adding elite strike-throwing prowess to his bat-missing ability.

There have been 36 pitcher seasons (min. 120 IP) since 2010* with a zone-contact rate of less than 83 percent. Of those 36 seasons, 11 saw their proclivity for whiffs accompanied by a 48 percent zone rate or higher. Three were by knuckleballers. Four were authored by Clayton Kershaw, two by Max Scherzer, one by David Price, and one by Duffy.

*I chose 2010 because the league’s zone rates and plate discipline profiles underwent dramatic changes between 2008 and 2010. In 2008, for instance, the league average zone rate was 50.5 percent. In 2010, pitchers were making hitters chase far more often, and the average zone rate was down to 45.4 percent. It’s been between 44.2 percent and 44.7 percent in every season since.


We’re going to invent something right now.

We’ll call it the Pitcher Approach Matrix. The X-axis runs from contact-oriented on the left to swing-and-miss-oriented on the right, as judged by zone contact rate. The Y-axis runs from zone-oriented at the top to chase-oriented at the bottom, as judged by zone percentage, obviously.

Can you see it? Yes? Isn’t it fun to create something together?

In this formerly hypothetical matrix that is now oh-so-real, the axes meet at the 2016 league averages for their defining measurements. That’s a 44.6 percent zone rate, and an 86.3 percent zone-contact rate. The edges of the matrix indicate the extremes reached by any pitcher who threw 120 IP in 2016.

Arrieta is actually the closest pitcher to that central intersection, by 2016 numbers, with Johnny Cueto not very far away. The most populous quadrant for starting pitchers (which is all we are concerned with here) is unsurprisingly the upper left-hand quadrant, where strike-throwing meets some contact, and where Bartolo Colon occupies the most extreme corner. The bottom-left quadrant features contact-oriented pitchers looking to make hitters chase, including our recent sources of wonder — Keuchel, and Hendricks. The bottom-right stocks more whiff-worthy stuff, but these pitchers, like Hamels, tend to throw it outside the bounds of the zone.

This is not meant to be overly scientific, as we are only examining one small portion of what makes a pitcher who he is. But his place here says something about not only his capabilities, but about what he thinks of his capabilities. That makes the upper right-hand quadrant the territory of pitchers who can miss bats, and who dare to do so in the zone.

And in 2016, Duffy set up shop deep in the heart of that territory.

We may circle back to the wider meanings of the matrix at a later date, but for Duffy, the implications seem pretty clear. If he can keep his fastball humming, and his slider snapping, at the same general level as 2016, he might be able to fashion himself in the image of Scherzer or Price.

Put differently, Duffy’s underlying performance doesn’t require us to search for an explanation of how it works. It doesn’t write the book on itself for opposing hitters.

All he has to do, it appears, is continue to pit his pitches against hitters’ abilities to hit them. In terms of breakout stories, it’s not quite as tactically interesting as testing the limits of the low strike, for instance, but it seems much more likely to last.

. . .

Zach Crizer is a featured writer at Beyond the Box Score. You can follow him on Twitter at @zcrizer.