Kansas City Royals Danny Duffy

Champions of the Changeup

The Kansas City Royals offense has been dreadful.

There, now that that’s out of the way, let’s talk about something more fun, like the Kansas City Royals starting rotation. It’s been extremely undreadful. They lead all of baseball in ERA, and the last time a Royals starter allowed more than one run was nine days ago. The rotation has been excellent, and outside of that first series, the bullpen has held their own as well. The biggest key to the pitching success has been their changeups.

Through Wednesday’s games, the Royals have been absolutely dominant with changeups. And “absolutely dominant” might be underselling it. According to data from Statcast, opposing batters are 15-100 against that pitch, with all 15 hits being singles. In case you don’t have a calculator near by, that’s a .150 batting average and a .150 slugging percentage. It’s also an isolated slugging percentage that is equal to my own isolated slugging percentage. And yours. And your infant’s.

Jason Vargas, Danny Duffy, and Ian Kennedy have combined to allow six hits in 60 at-bats that end on a changeup. Vargas’ .107 average allowed is the highest in that trio. Add in Nathan Karns and his .154 average allowed on the pitch, and you can see how the rotation has rolled to that league-best ERA thus far. Because when a pitch is as effective as the changeup has been for Kansas City, it makes sense to throw quite a few of them.

Royals pitchers have thrown 380 changeups through Wednesday’s action this season, which is a rate of roughly 18.6 percent. The next-highest rate belongs to the Indians, at 13.9 percent. Put another way, the difference between the Royals changeup rate and the second-highest changeup rate is as large as the difference between the second-highest changeup rate and the 19th-highest changeup rate (Astros, 9.2 percent).

Vargas has always leaned on his elite changeup,¬†and he’s continuing to throw it roughly 30 percent of the time. Our own David Lesky recently wrote about Duffy’s changeup, and as he’s carried over last season’s success with it, he’s increased its usage from 17 percent in 2016 to more than 27 percent in 2017. Both of those pitchers rank in the top ten changeup rates among those with at least 150 total pitches thrown, and Karns checks in at 14, with a rate of nearly 25 percent. Kennedy has only thrown 44 changeups out of his 305 pitches, but he’s also induced 16 whiffs with it. And that brings us to another aspect of this staff’s changeup dominance: whiffs by the bushel.

As a team, the Royals have gotten 86 whiffs with changeups. Once again, that’s the most in baseball. Once again, the second-highest total belongs to the Indians, and once again, that total is not in the Royals’ stratosphere. They’re at 54, which is an excellent whiff rate of 17.1 percent. The Royals’ whiff rate is sitting at 22.6 percent. For perspective, Stephen Strasburg had a changeup whiff rate of 22 percent last season. They’re not quite in Cole Hamels territory, but it’s been an unbelievably effective pitch for several Royals, which has led to their remarkable start.

“On pace for” stats are always stupid this early in the season, but I’m going to present you with one anyway:

The Royals are on pace to induce approximately 1,000 whiffs with changeups.

See! Look at how stupid that stat is! It’s absurd!

Last year the Royals were one of the best at getting swings and misses with changeups, and they “only” induced 550 of them. That was the second-highest total in baseball, trailing the Angels, who were at 778. The Angels’ whiff rate on the changeup was about 15.5 percent. The Royals’ whiff rate was 17.3 percent. This year’s squad is obliterating those numbers.

Having said that, it certainly seems like we should expect some regression. There are quite a few top-notch changeups amongst Royals pitchers, and even if they don’t maintain this pace, they’re still going to miss plenty of bats. They might even allow an extra-base hit or two, at some point. That won’t change what’s been done to this point, however. Led by Vargas, Duffy, and Kennedy, the Royals have been masterful on the mound, and they have their changeups to thank.

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