What Are the Nastiest Pitches in the KBO?

MLB fans can rattle off some of the best pitches in the game without any problem. Whether it’s Gerrit Cole’s fastball, Clayton Kershaw’s curveball, or Chaz Roe’s slider, you know who throws filth. But what about in the KBO? There are plenty of excellent pitchers in the KBO, former MLBers and otherwise, but it has been tough to evaluate their particular pitches. With MLB guys, it’s one trip to Baseball Savant and you know who throws the best fastball in the game in a few minutes.

That’s why I created the KBO Wizard, a tool to host advanced stats that I’ve tracked from watching KBO games. The newest feature? Pitch type breakdowns that allow you to view pitcher’s success and stats on individual pitches. Pair that with the eye test and I feel confident that these are some of the best pitches in the KBO among pitches that have been thrown 100+ times (with one exception). If you disagree with me, check out the KBO Wizard and let me know why on Twitter @benhowell71. But these are my picks for the best pitches in the KBO:

Aaron Brooks’ Changeup

There’s no other pitch in the KBO that I enjoy watching more than a good changeup from Aaron Brooks. Just look at the way that pitch drops off as it approaches the plate. At an average of 85 mph, how do you hit this squarely? I could watch changeups from Aaron Brooks on a loop all day.

If you have the answer to that question, the KBO teams that have to face Brooks would like to know. He throws his changeup almost exclusively against LHH, using it a total of 21% of the time and it always breaks down and away from LHH. It produces a 23% Whiff%, making it Brooks’ best swing-and-miss pitch that he uses regularly, despite 23% being a relatively average Whiff%, but that’s not the purpose of Brooks’ changeup.

Among pitches thrown 100+ times in the KBO that I’ve charted, Brooks has a whooping 72% groundout rate on balls in play, far and away the best mark, beating Ben Lively’s sinker by 15%. It has the lowest fly out ratio at 2.8% and tied for the second-lowest XBH rate at just 2.8%. With his changeup’s 57% swing rate (second amongst pitches thrown 100+ times), that’s a lot of easy groundouts. That’s a big reason that Brooks has the highest groundout rate overall and second-lowest XBH rate among pitchers with 300+ pitches overall.

Aaron Brooks’ changeup might be my favorite KBO pitch to watch because of the way it moves and it’s success is hard to argue with. His changeup is a huge reason why Brooks has been so successful this season, posting an ERA of 2.60 and FIP of 2.91, the fourth and second-best marks among qualified pitchers this season. Just watch that GIF at the top again and imagine trying to hit that pitch; I’d bet you couldn’t or it wouldn’t go very far.

Dan Straily’s Slider

By most counts, Dan Straily has been the second-best pitcher in the KBO this year, with the third-best K/9 of 9.10, the second-best WHIP of 1.00, and second-best ERA of 2.04. How has he done it? With his slider, an absolutely nasty pitch.

He’s thrown his slider about 37% of the time this season, averaging 84 mph, and against LHH and RHH, which is a little bit surprising, but it’s extremely effective in two ways. Straily throws his slider down and away from RHH and on the edges of the strike zone against LHH. His slider has induced a whiff rate of 41% this season, second-best in the KBO, but the best swinging strike rate at 26%. But what really sets his slider apart if the 18% called strike rate that he gets; no other pitch that has been thrown 100+ times has an SwStr% above 20% and CS% above 15%. Most pitches are either good for called strikes or swings and misses; Straily gets both with just one pitch, resulting in a Called Strike + Whiff% of 43% on his slider, leading the KBO as the only pitch above 40%.

With the way that his slider breaks away from RHH and towards LHH, Straily’s slider is a really tough pitch for hitters to get the bat on as they prove time and time again. Straily’s slider doesn’t show any sign of slowing down and could be the pitch he rides back to an MLB roster spot.

Koo Chang-Mo’s Splitter

If you’ve been following the KBO at all the last few months, you’ve almost definitely heard the name Koo Chang-mo and for good reason. His 10.24 K/9 mark leads the KBO and he’s tops in both ERA and FIP, with marks of 1.55 and 2.77. A big reason for that, and what lands on this list, is his nasty splitter that hitters are finding impossible to hit. This pitch was the sole exception to my 100+ pitches rule; I’ve only charted Koo throwing his splitter 43 times for a 21% usage rate, but you’ll see why I waived that rule.

Koo’s splitter has produced a whiff rate of 46% in the starts I’ve watched, averaging about 81 mph as he locates it down and away from RHH. That equals a 30.2% swinging-strike rate, blowing by anything else in the KBO that I’ve tracked. That’s led to a ridiculous 79% strike rate on his splitter, second place only to Dan Straily’s slider, despite throwing his splitter out of the zone so much.

Drew Rucinski’s Slider

Drew Rucinski would be an ace for most KBO teams, but he’s the #2 for the NC Dinos behind Koo Chang-mo and his splitter. Rucinski’s ERA of 2.88 is sixth in the KBO and the end of the top tier of pitchers as David Buchanan ranks seventh at 3.70. Rucinski has only been striking out 7.70 batters per 9 this season but has been really successful at limiting hits allowed, with a batting average allowed of just 0.234, seventh-best in the KBO.

That’s where his slider comes in. Averaging around 86 mph and throwing it 21% of the time, Rucinski’s slider is used when he’s needs to get hitters out. His slider has a whiff rate of 43%, tops among pitches thrown 100+ times, good for the second-best swinging strike rate of 23%. His slider doesn’t have the most side-to-side movement the way a pitch like Dan Straily’s does, but is more up and down, messing with hitter’s timing off of his fastball.

It’s been a successful combo. In addition to his stellar whiff rate, Rucinski’s slider has also induced a groundout rate of 41% and an XBH% of 0%. When hitters do manage to make contact, the ball isn’t getting hit very hard or going very far, exactly what the pitcher wants. Rucinski has thrown the slider against both RHH and LHH and the approach has worked and I’m interested to see if he uses the slider more as the season continues.