Predicting Jung-ho Kang’s Performance in the US

By Byung Joon Yoon

Last time, we checked defensive projections and part of offensive projections of Jung-ho, namely, predicting how he will do if he were to move to Japan. Now, as second part of offensive projection, I will draw data from performance change in players who moved from Japan to US, and apply that to Jung-ho’s predicted performance in Japan to predict his performance in US. Note that this is not perfect because of insufficient sample size, change in league level over the years, and double counting performance drop from transition, but hopefully it can provide baseline on what to expect.

Below is data from 12 players who played at least one season in MLB after moving from NPB to MLB:

JPN   AVG OBP SLG OPS ISOP
Suzuki Ichiro 0.353 0.421 0.522 0.943 0.169
Norichika Aoki 0.329 0.402 0.454 0.856 0.125
Shinjo Tsuyoshi 0.254 0.305 0.432 0.737 0.178
So Taguchi 0.276 0.332 0.384 0.716 0.108
Hideki Matsui 0.304 0.413 0.582 0.995 0.278
Kazuo Matsui 0.297 0.348 0.462 0.81 0.165
Tadahito Iguchi 0.272 0.36 0.455 0.815 0.183
Kenji Johjima 0.296 0.355 0.508 0.863 0.212
Akinori Iwamura 0.29 0.358 0.494 0.852 0.204
Kyosuke Fukudome 0.296 0.388 0.52 0.908 0.224
Tsuyoshi Nishioka 0.292 0.361 0.419 0.78 0.127
Munenori Kawasaki 0.294 0.345 0.378 0.723 0.084
US   AVG OBP SLG OPS ISOP
Suzuki Ichiro 0.317 0.36 0.411 0.771 0.094
Norichika Aoki 0.287 0.353 0.387 0.74 0.1
Shinjo Tsuyoshi 0.245 0.299 0.37 0.669 0.125
So Taguchi 0.279 0.332 0.385 0.717 0.106
Hideki Matsui 0.282 0.36 0.462 0.822 0.18
Kazuo Matsui 0.267 0.32 0.38 0.7 0.113
Tadahito Iguchi 0.268 0.338 0.401 0.739 0.133
Kenji Johjima 0.268 0.31 0.411 0.721 0.143
Akinori Iwamura 0.267 0.345 0.375 0.72 0.108
Kyosuke Fukudome 0.258 0.359 0.395 0.754 0.137
Tsuyoshi Nishioka 0.215 0.267 0.236 0.503 0.021
Munenori Kawasaki 0.235 0.315 0.284 0.599 0.049
Difference Avg Diff OBP Dif SLG Dif OPS Dif ISOP Dif
0.036 0.061 0.111 0.172 0.075
0.042 0.049 0.067 0.116 0.025
0.009 0.006 0.062 0.068 0.053
-0.003 0 -0.001 -0.001 0.002
0.022 0.053 0.12 0.173 0.098
0.03 0.028 0.082 0.11 0.052
0.004 0.022 0.054 0.076 0.05
0.028 0.045 0.097 0.142 0.069
0.023 0.013 0.119 0.132 0.096
0.038 0.029 0.125 0.154 0.087
0.077 0.094 0.183 0.277 0.106
0.059 0.03 0.094 0.124 0.035
Average 0.030417 0.035833 0.09275 0.128583 0.062333
St.Dev 0.022593 0.026281 0.045711 0.067739 0.031984
Correlation 0.619279 0.664825 0.710128 0.687719 0.811897

As you see, correlation is pretty good in all statistics. However, to maximize overall correlation, I will construct regression line for SLG, OPS and ISOP and calculate slash line from there.

OPS: USOPS= 0.158+0.656*JPNOPS

SLG: USSLG= 0.047+0.7*JPNSLG

ISOP: USISOP = 0.002+0.625*JPNISOP

Estimated performance of Jung-ho Kang in US

OPS : 0.649 with SLG: 0.346 and ISOP : 0.104 = 0.242/0.303/0.346/0.649

So, my final prediction is that he will hit 0.242/0.303/0.346/0.649 in US, which isn’t that bad considering that average slash line for shortstop in 2013 was 0.254/0.308/0.367/0.675 while earning $4.5 million. Also, considering that he is only 27, just had his best season to date with OPS 1.198, and the method I used double counted effect of moving to new location, there is a good chance that this prediction is underestimated. Provided that his defense is adequate and he can play shortstop in MLB, I think he will be able to contribute and there will be teams interested in his service.

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