When the Pirates signed Jung-ho Kang out of Korea, there was a lot of speculation over just how good Kang would be, and how much playing time he could get with Pittsburgh. Before Kang, a Korean position player had never jumped into the majors. The Pirates also had a perfectly decent starting shortstop in Jordy Mercer, so it wasn’t the most likely of destinations for a power hitter like Kang. However after a bit of a slow start, Kang is batting .313/.378/.444 and has settled into the 5th slot in the Pittsburgh lineup. The prodigious power he displayed in Korea hasn’t exactly translated to the States just yet (only two homers thus far), but he’s still managed a 133 wRC+. How has he managed it?
One of the major concerns about Kang was that the big leg kick in his swing would lead to a lot of strikeouts. It wasn’t a completely unreasonable worry. The Korean league (the Korean Baseball Organization, or KBO) had a collective ERA over 4 last season, and has made stars of big league washouts like Felix Pie and Eric Thames. Kang had been facing much worse pitching with fairly unorthodox batting mechanics.
As you can se in the above highlight reel, whenever Kang went yard in Korea he incorporated pronounced leg kick. He also used it to hit a towering shot off Trevor Rosenthal to hit his first stateside blast. The leg kick is still showing up as recently as this week. However, here's what Kang's swing looked like on May 10th when he victimized Tyler Lyons.
The kick is conspicuously absent. Instead, Kang utilizes the smallest of strides before letting his hips and arms do all the work in getting to the 93 MPH heater that Lyons left out to dry. It's a fascinating little adjustment for Kang in what's been a remarkably good season, and he's only struck out 18 percent of the time. Not including Wednesday's game in which he notched a single and two RBI's, Kang's put up 1.3 fWAR in only 107 plate appearances. Among shortstops with at least 100 plate appearances, that's tied with Freddy Galvis and Jhonny Peralta for third in the game. The current fWAR leader in the NL (and all of baseball) is Brandon Crawford of the Giants. Crawford is enjoying a fabulous breakout season at the plate (148 wRC+) to go along with his usual great defensive play. His .299/.379/.508 line has come in 174 plate appearances.
Kang's measly 107 plate appearances gives him a chance to catch Crawford or get pretty close to him in terms of net production before the All-Star Game, if we want to ascribe to the hairy idea of "on pace for ___." This isn't to say that Crawford hasn't played his way into having a great case to be in the starting lineup in Cincinnati. Would it be an absolute shock to see Kang surge into Crawford's territory? Possibly. It also wouldn't be a shock to see Kang regress. The former KBO MVP sports a high .372 BABIP while 59.7 percent of his balls in play end up as ground balls. Eventually, more of those grounders are going to find infielders and Kang's OBP will come down. There's also the matter that 12.5 percent of his fly balls aren't leaving the infield and therefore becoming popups. That's a rate that will likely come down, so it's quite likely that we haven't seen the final form of Kang's profile as a hitter in MLB.
If Kang can keep up his BABIP wizardy a while longer, he's got a great shot at an All-Star selection. His Crawford-esque mix of offense and defense will take him there. Should he start? Odds are regression takes its toll on his numbers but GM Neal Huntington should be very proud of this signing.