Jung Ho Kang Passed the Fastball Test

The worry is always the same whenever an Asian hitter comes over. The hitter wouldn’t be getting the chance in the first place were it not for an outstanding performance, but there’s always the question of how the hitter is going to handle major-league fastballs. In part, this might just come from arrogance, but it’s not without its legitimacy. Many Asian hitters have high leg kicks that work as timing mechanisms, and more importantly, there just isn’t a lot of big velocity in South Korea or Japan. The hitters are mostly unproven against the stuff you find in almost every big-league bullpen. So, it’s fair to wonder how a player might adjust.

What we already knew from last season: Overall, Jung Ho Kang adjusted. Kang was so successful, in fact, opportunities have been given to other Korean hitters. Because Kang did so well, it won’t surprise you to learn he did well against fastballs. I’m only writing this because of how Kang has been pitched this year since coming back from injury. Kang has worked beyond the fastball test. Pitchers would rather let him see almost anything else.

Kang returned to the Pirates a little under a month ago. Since that point, he’s slugged an outstanding .600. To dig in a little, a handful of Pirates have batted at least 50 times over the past 30 days. What I’ve done here is plot player wRC+ and player rate of fastballs seen:

I don’t care about trying to draw a correlation. No point in doing that over one month of games. What stands out: Not only has Kang hit, but he’s seen very few fastballs. He’s seen easily the lowest rate on the team, just barely clearing 40%. I like to do the team-wide comparisons just to check if maybe it has something to do with the identities of the opposing pitchers. It’s like a check to see if the Pirates have just faced guys who don’t throw many heaters. That’s not the case — they just haven’t thrown Kang many heaters.

And there’s no need to stop there. Over the past 30 days, all around baseball, 282 different players have batted at least 50 times. Kang has the very lowest rate of fastballs seen, just lower than Mark Trumbo. No mystery why pitchers don’t want to give Trumbo any fastballs. The same thing applies to Kang. And to go just one step further, gathering numbers from both 2015 and 2016, no player in the game has seen a bigger year-to-year drop in fastball rate. Kang’s fastball rate is down more than 13 percentage points. Corey Dickerson’s is down a significant 11 percentage points, and that’s because he’s hunting fastballs. The perception is that he’ll kill them. That’s also the perception with Kang. There’s no other good explanation.

It’s not like that means Kang doesn’t have any weaknesses. He does, after all, have two walks and 15 strikeouts. What this means is that, given the choice between a heater and a non-heater, pitchers think they have a better chance of getting Kang out with a non-heater. Batters who can be exposed by fastballs see high rates of fastballs. Consider this year’s version of Jason Heyward. In the collective opinion of major-league baseball, Kang is not vulnerable to heat. That’s what the pitch rates suggest.

Again, the general significance of this isn’t new. Through more than 500 trips to the plate, Kang’s got a 131 wRC+, to go with a .479 slugging percentage. He’s pretty clearly made things work just fine for himself. I just do think it’s worth noting the primary way by which he’s been successful. Last year, he slugged in the mid-.500s against fastballs, tying Justin Upton, a year before that would become an insult. This year, Kang has somehow slugged .971 against fastballs, behind only teammate Matt Joyce(??) at .973. Where we are now: overall against fastballs, Kang’s slugged .597. Since the start of last year, Giancarlo Stanton is at .602. Miguel Cabrera is also at .597.

It’s fun to just cruise through the splits. According to Baseball-Reference, Kang has been better against relievers than he’s been against starters. He’s been better against power pitchers than he’s been against finesse-y opponents. He’s been at his best in high-leverage situations, when there’s the greatest focus on how to get him out. It doesn’t matter where you look. All the evidence keeps pointing to the idea that Kang has adjusted to major-league velocity, and he apparently did it almost overnight. Only now are pitchers shying away from their heaters, trying to get Kang to expand. He’s not being pitched like a Korean import with a potential vulnerability. He’s being pitched like a power hitter. Probably because he’s a power hitter.

Jung Ho Kang doesn’t prove anything about Korean or Asian hitters in general. There will be concerns about every single one, just as there are concerns about every single untested prospect. You don’t know how someone will do in the majors until that very someone gets a shot in the majors. The Pirates must be beyond ecstatic they gave that shot to Kang. Kang has handled everything thrown at him, and after this long, opposing pitchers are running out of new tricks. Fastballs haven’t worked. Kang has seen to that.