Hee-Kwan Yoo’s Deception Leads to Bears Success

The pitcher’s atypical arsenal lends itself to trickery and soft contact

While negotiations between the MLB Player’s Union and the owners of the big-league clubs drag on, the Korean Baseball Organization has begun its season, with a game per day broadcasted on ESPN, helping to fill our need for baseball.

Last night, the SK Wyverns and Doosan Bears faced off. The Bears won 4–2 thanks to a strong pitching performance by 33-year-old Hee-Kwan Yoo, in his 10th year in the KBO, all with the Bears. Yoo paired his below-average fastball with his looping 12–6 curve and knowledge of his opponent to work around trouble and into favorable outcomes. Here, I’ll be diving a little deeper into Yoo’s performance, starting with a post-game report that I put together while charting his outing.

Yoo pitched 7 innings of one-run ball, but what stood out to me was his pitch count: 110 pitches. In the 2019 MLB season, there were only 110 games where the pitcher threw 7+ IP and 110+ pitches, making this already a different experience from the typical MLB game.

But it’s HOW Yoo accomplished that was surprising. He’s able to pitch deeper into games and throw more pitches because his velocity is so much lower than the average MLB hurler. His 4-seam fastball velocity hovered around 80 MPH, with his looping 12–6 curveball coming in around 62 MPH, a completely separate pitch from his fastball combo.

While his velocity is starkly lower than MLB counterparts, the approximately 18 MPH difference between his curve and 4-seamer is pretty typical and allows him to perform with that lowered velocity. As the density plot above indicates, Yoo works within very specific ranges. Nearly every time Yoo threw a low 60s curve, he followed it up with a fastball in the 78–81 range. Deception at it’s finest by disguising the speeds that pitches are coming in at by mixing and matching to alter the hitter’s perception.

However, Yoo doesn’t miss a lot of bats, only getting 8 swings and misses in his last start and just 5 strikeouts. Throughout his career, he’s never been that guy, with his career-high K/9 of 6.75 coming way back in 2009, his rookie year.

Instead, as the table indicates, Yoo makes do with good control, limiting his walks allowed and allowing soft contact. Yet, his BB/9 rate has almost doubled from 2019, which has led to his increased FIP early in the season.

And it was those walks that hurt Yoo against the Wyverns. He walked 4 batters in just 7 IP, a worse rate than his season average, and, at one point, had a stretch of 8 straight balls in the 2nd inning, resulting in 2 walks, one of which walked in a run with the bases loaded.

Yet, the way he navigated that bases-loaded jam is a sign of how he navigates his starts. The first walk of those two loaded the bases, bringing up Jamie Romak, a former MLB slugger who posted a 147 and 140 wRC+ in the KBO the last two seasons. After falling behind early to Romak, Yoo pitched around him to bring up Jin-gi Jeong who had a wRC+ of 48 in 2018, the last time he saw 100+ at-bats in a season. That’s a really smart decision to work around a dangerous hitter to bring up one who is way below average. And it worked too! Jeong grounded out weakly to end the 3rd inning with only 1 run scored.

A similar situation presented itself in the 5th inning when Romak came to bat with runners on 1st and 3rd with two outs after another walk by Yoo. This time, after a first-pitch strike (of which Yoo threw 18 to his 28 batters faced for a 64% first-pitch strike rate, about average), Yoo pitched around the edge of the zone, eventually drawing a soft fly out from Romak on a 3–2 count.

While Yoo allowed contact on 82% of opponent’s swings, they only had a BABIP of 0.211, indicative of Yoo’s ability to limit hard contact through his pitch mixing and speed changes. On the balls that were hit, most of them were ground balls and ground outs, rather than the more dangerous fly outs that can lead to increased HR rates allowed.

It’s not always pretty but Yoo’s 12–6 curveball and the velocity differences between his curve and fastballs gives him a path to success, especially when he knows how to navigate a lineup, as he proved he does by working around Jamie Romak twice in dangerous situations.

Sophomore studying Sport Management and Economics at the University of Texas. Writing about Baseball from an analytical and scouting perspective

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