Behind the Switch-Hitting of Ji-Man Choi

Written by: Justin Choi (@justinochoi)

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Ah, the joy of Ji-Man Choi. Ask me who embodies the fun, goofy aspects of baseball and I’d have to go with him. His transformation into a swerving airplane after hitting a walk-off homer is one example of his lovable personality. And how can you not appreciate his smile? 

On top of that, Choi is a solid baseball player – during his first full season with the Rays in 2019, he walked and slugged his way to a 121 wRC+. During the ALDS, he became sort of a folk hero with a diving stop at first base and by drawing 3 walks against Justin Verlander. We’ve been paying attention to him ever since. 

In 2020, Choi has managed to amaze us again. Not through his on-field results, unfortunately; the 80 wRC+ he carries this season is the fifth-lowest amongst first basemen with at least 70 plate appearances. The source of our excitement came from a single home run. It’s one of two he’s hit so far, but it’s more than just a home run: 

Ji-Man Choi had spent his entire major league career as a left-handed hitter. Against Anthony Kay, he stepped into the batter’s box adjacent to where he usually stood – and obliterated the first pitch he saw! 

Choi, to my surprise, had tried switch-hitting when he was in the Mariners’ farm system between 2010 and 2015. It didn’t work out, and he stuck to batting from one side. It’s been years since then, which is why he looks awkward against Kay, as if someone photoshopped a bat into his open hands. The ability to absent-mindedly tattoo a fastball into left center is perhaps a testament to his raw power. 

But this one at-bat goes a bit deeper than you think. First, let’s consider the pitcher facing Ji-Man Choi: Anthony Kay. The number-four Blue Jays prospect is a southpaw, and therefore has more difficulty dealing with right-handed batters. In a short span of 14 innings pitched last year, Kay allowed 8 runs against them while allowing just one against left-handed hitters. In terms of ERA, that’s 6.55 versus 3.00.  

Second, the 90 mph fastball he threw? That’s a complete mistake pitch – since then, Kay has averaged a crisp 94.1 mph on his fastballs. This, combined with an above-average spin rate of 2343 per minute, induced hitters to whiff 39.1% of the time. The horizontal and vertical movement the pitch generates is underwhelming, but that’s beside the point. What these numbers illustrate is that although Choi is a skilled hitter, he got a little lucky. 

But this isn’t where our story ends. On August 16th, at Sahlen Field, Buffalo, Ji-Man Choi had a rematch against Anthony Kay. Only this time, Choi hit left-handed as usual. As for Kay, he led off with his curveball. And one more detail: there was an attempt to swing. Here’s a preview of all I’ve said: 

Except for the first-pitch swing, both sides clearly had different strategies – is there an explanation as to why? Digging through some splits gave me an answer. 

Let’s start with Choi. Despite his high career strikeout rate and current gross-cover-your-eyes rate of 35.2%, he’s a good breaking ball hitter. Narrowing our focus to curveballs, here’s how he fared against them in 2019 and this season. The league averages are included as a comparison point: 

His 2020 numbers are admittedly from a very small sample of two walks and a double, but a full season’s worth of taking and teeing off curveballs proves our point. That’s not all. When Choi swung at the first pitch in 2019, he produced a wOBAcon of .402 regardless of pitch type; on all other counts, that dwindles to just .300. Being aggressive early makes up a significant chunk of Choi’s production. 

So that’s it, right? Choi swung at a pitch he likes, on a count he likes, so he must have made good contact. Not so fast. Kay is also confident about curveballs – it’s arguably his best pitch. Despite it having a CSW% (called strikes + whiffs%) of just 22.2% throughout 2019 and 2020, it’s allowed a paltry .109 wOBA. 

Call that result luck-driven, but nevertheless this isn’t an average curveball that Choi can feast on. The pitch has tacked on more vertical movement this season, which may help Kay moving forward: 

In addition, Kay exploited a weakness. Here’s a grid from Fangraphs showing Choi’s ISO/BIP throughout his career (from the pitcher’s perspective). The metric is somewhat noisy, but that’s mitigated by our large sample size: 

Choi’s hot zones, as indicated by red, are clear: he crushes pitches that are down and in, up and away. The pools of deep blue, in contrast, suggest that he struggles with pitches that are down and away from the pitcher’s perspective. Not only does he whiff a ton, but the results are disappointing even when he does make contact. 

So this truly isn’t any curveball. It’s an improved one that Kay threw with meticulousness, hoping to redeem himself from his previous defeat. 

Finally, here’s what actually happened. Choi enthusiastically swung and missed at that curveball, bringing the count to 0-1: 

He then whiffed at the exact same pitch, 0-2: 

And after a foul ball, the at-bat ended with a groundout: 

To drive the point home, here are the locations of all four pitches Kay threw to Choi: 

Yep, all curveballs, all to quadrants of the zone Choi has had trouble mastering. Kay gave him absolutely nothing to work with this time and rightfully escaped the jam. 

A few people wondered why Choi didn’t bat right-handed against Kay again, and my theory is this: the Rays knew that Kay and the Blue Jays would arrive prepared. This prompted the decision to let Choi hit comfortably – he is a good breaking ball hitter after all. Swing at the first pitch, try and launch a curveball away. 

Unfortunately, Kay executed his plan perfectly, and well, as a hitter there’s not much defense against that. What’s ironic, though, is before retiring Choi, he had walked 3 batters to load up the bases. Maybe all his pre-game prep was focused on avoiding getting embarrassed by the Ji-Man? His jittering forearm is a tell: 

Had Ji-Man Choi stood as a right-handed hitter, recorded a hit off him, the baseball community would have continued to sing his praises. But because Choi stuck with what he knew – a good decision, in fact – and Kay brought his absolute A-game, the world has forgotten about his switch-hitting adventures. In fact, Choi has expressed doubt on whether he would continue to switch-hit. 

Baseball is defined by winners and losers, after all; the on-field results determine how much we enjoy or admire a player, and whether said player does or doesn’t change his approach. 

But sometimes, looking at the process, the behind-the-scenes, can be just as entertaining. Case-in-point: this article, which allowed me to take a deep dive into the strengths and weaknesses of Ji-Man Choi and Anthony Kay. Had Choi succeeded, I probably wouldn’t be here. The two are currently tied at one in their battle, and it’ll be interesting to see who prevails by the end of the season. 

Follow P365 MLB and KBO Analyst Justin Choi on Twitter! @justinochoi

Follow us on Twitter! @Prospects365

Featured image courtesy of the Tampa Bay Times

All statistics from Baseball Savant, Brooks Baseball, and Fangraphs

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