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Nate Karns could be a valuable asset for the Royals

Ignore the ERA. The Royals righty has become a far better pitcher this year.

MLB: Kansas City Royals at Chicago White Sox
Focus on the foreground, and try to ignore what’s in the background.
Caylor Arnold-USA TODAY Sports

2017 hasn’t gone as planned for the Royals. The team retooled in the offseason, trading away stalwarts Wade Davis and Jarrod Dyson, but in giving Danny Duffy a five-year extension, Dayton Moore indicated he wasn’t ready to give up yet. A 12-21 record thus far — the worst in the American League — might have changed those plans.

The good news: If Kansas City rebuilds this year, it’ll have no shortage of quality players to deal. Mike Moustakas, Lorenzo Cain, and Eric Hosmer will both be free agents at year’s end, and they’re each regarded (fairly or not) as some of the best players at their respective positions. Jason Vargas is also playing in his walk year, and he’s somehow become one of the best pitchers in baseball.

But the Royals have another sneaky-good player they might trade — if he stops allowing so many runs. Acquired for Dyson during the offseason, Nate Karns has an unimpressive 4.58 ERA and 4.38 FIP through seven games. Beneath that, though, lurks some sleeper potential. Karns has a 3.35 DRA over his 35 13 innings pitched; his 74 DRA-, adjusted for the league environment, is easily the best of his career.

This progress stems from a couple of areas. Karns’s ground ball rate has spiked to 56.7 percent this year — the eighth-highest in baseball, and a level he’s never come close to before:

Image via FanGraphs

And even better, he’s actually increased his whiff rate to 12.1 percent, which has helped him maintain a 24.1 percent strikeout rate. Keeping the ball on the ground, and getting strikeouts when you don’t, is pretty much always a recipe for success.

To understand how he’s made this leap, we need to break down Karns’s arsenal. He’s always rolled with four primary pitches — a four-seam fastball, a sinker, a curveball, and a changeup. This year, the latter has taken on a larger role:

Image via Brooks Baseball

Karns worked on perfecting the changeup during spring training, and his labor seems to have paid off. The cambio’s ground ball rate has spiked to 66.7 percent, while its whiff rate has held steady at 13.4 percent. That’s given him another weapon to attack hitters with.

The changeup isn’t Karns’s best pitch, though. When he wants to put a hitter away, he’s always turned to the curveball, which has done better than ever in 2017. Its 67.9 percent ground ball rate is one of the highest in the majors, and its whiff rate doesn’t need that qualifier:

Curveball whiff leaders — 2017

Rank Player CB CB Whiff%
Rank Player CB CB Whiff%
1 Nate Karns 183 25.1%
2 Madison Bumgarner 68 25.0%
3 Luis Perdomo 104 24.0%
4 Carlos Carrasco 78 21.8%
5 Trevor Cahill 138 21.7%
6 Charlie Morton 153 21.6%
7 Lance McCullers 288 20.5%
8 Jesse Hahn 98 19.4%
9 Clayton Richard 100 19.0%
10 German Marquez 67 17.9%
Ranking among 83 starters with at least 50 curveballs thrown in 2017. Data via Baseball Prospectus

Karns throws his curveball super hard — it ranks fourth in that sample with an average velocity of 84.2 mph, regaining some of the power it had earlier in his career. Plus, he’s started to concentrate its location below the strike zone:

Images via Brooks Baseball

The vertical location on his curve has dropped off a cliff — seriously, check out this hilarious graph. Before 2017, Karns threw 47.5 percent of his curveballs below the Brooks Baseball strike zone; this year, he’s pumped that up to 57.2 percent. This has the double effect of (a) more whiffs and (b) more grounders.

So with an improved changeup and a dangerous curve, why does Karns have such a pedestrian ERA? He’s come down with a bout of gopheritis, allowing six long balls in his 35 13 innings. That shouldn’t persist, though; his exit velocity is below the major-league average, and so is his hard contact rate. Once his 19.4 percent home run/fly ball rate normalizes, he should keep some runs off the board — a skill teams would pay handsomely for.

Karns had a 5.15 ERA in his lone year with the Mariners; when the Royals traded for him in the offseason, they were buying low, hoping he’d bounce back. Their wish has come true — Karns has revamped his arsenal and become a high-grounder power pitcher. Hosmer, Moustakas and some other free-agents-to-be are struggling a bit, but Karns is pitching better than ever. With three years of team control beyond 2017, he could fetch a decent return come July.


Ryan Romano is the co-managing editor for Beyond the Box Score. He also writes about the Orioles for Camden Depot, sometimes. Follow him on Twitter if you enjoy angry tweets about Maryland sports.