I looked at 2008 and 2009 Ni-gun numbers, giving enough time for pitchers to either establish themselves or fail in the NPB. I used the first year recorded average velocity in the NPB. Of course there is survivor bias, as we only get MPH data from those who pitch in the actual NPB, and thus only use those players (and only players I could find, as I had a problem with a couple of the names). I hate using ERA, but we are using the Ni-gun ERA, partially just because it is easier. I used career NPB FIP (or nFIP) as the determining factor for who fared the best in the NPB (because it translates best from ERA, rather than using a WAR based metric and comparing it to Ni-gun ERA).
Sorted by velocity:
Maximo Nelson: 92.53 MPH, .56 Ni-gun ERA, 3.71 nFIP
Michael Schultz: 92.38 MPH, 1.50 Ni-gun ERA, 2.76 nFIP
Daisuke Yamai: 89.82 MPH, 2.38 Ni-gun ERA, 3.68 nFIP
Akinobu Shimizu: 89.13 MPH, 3.69 Ni-gun ERA, 3.77 nFIP
Masafumi Hirai: 88.84 MPH, 1.96 Ni-gun ERA, 4.28 nFIP
Yohei Yanagawa: 88.42 MPH, 2.81 Ni-gun ERA, 2.89 nFIP
Naoto Tsuru: 88.37 MPH, 3.34 Ni-gun ERA, 3.93 nFIP
Hidetaka Kawagoe: 88.28 MPH, .68 Ni-gun ERA, 4.14 nFIP
Tomoyuki Kubota: 88.12 MPH, 2.59 Ni-gun ERA, 3.48 nFIP
Hiroki Kongo: 88.09 MPH, 3.21 Ni-gun ERA, 3.90 nFIP
Kentaro Hashimoto: 88.07 MPH, 2.14 Ni-gun ERA, 4.48 nFIP
Ken Nishimura: 87.83 MPH, 2.20 Ni-gun ERA, 3.35 nFIP
Singo Tatsumi: 87.78 MPH. 4.87 Ni-gun ERA, 8.41 nFIP
Tatsya Kajimoto: 87.69 MPH, 4.29 Ni-gun ERA, 6.84 nFIP
Keisuke Imai: 87.60 MPH, 3.75 Ni-gun ERA, 4.07 nFIP
Atsushi Nohmi: 87.50 MPH, .83 Ni-gun ERA, 3.01 nFIP
Atsushi Nakazato: 87.35 MPH, 2.75 Ni-gun ERA, 3.96 nFIPShinsuke Ogura: 86.82 MPH, .43 Ni-gun ERA, 4.98 nFIP
Toru Takahashi: 85.77 MPH, 3.49 Ni-gun ERA, 5.1 nFIP
Hirofumi Ueno: 85.75 MPH, 1.69 Ni-gun ERA, 4.95 nFIP
Hayato Aoki: 83.52 MPH, 4.74 Ni-gun ERA, 4.37 nFIP
Tatsuya Kojima: 83.37 MPH, 3.29 Ni-gun ERA, 3.67 nFIP
Mean velocity is 87.865 MPH for these players (meaning the average velocity of these pitchers is lower the average KBO rotation velocity). There isn't a large deviation in velocity in these pitchers, with a heavy concentration of pitchers throwing 87-88 MPH.
Top 5: 3.64 nFIP
6-10: 3.67 nFIP
11-15: 5.43 nFIP
16-22: 4.29 nFIP
These findings are very similar to what we saw in the KBO velocity article. The best pitchers are the hardest throwing ones, while the ones closer to the mean are the worst and the softer throwing ones are better than the ones close to the mean.
When we sort the players by their Ni-gun ERAs, it didn't predict the best 10 pitchers as well, but it predicted the bottom pitchers better than sorting by velocity did.
Top 5: 3.72 nFIP
6-10: 4.15 nFIP
11-15: 3.63 nFIP
16-22: 5.18 nFIP
So it seems, that in the NPB Ni-gun, you can predict with a decent expectation of success who will be the best pitchers in the NPB by their velocity, or even their Ni-gun numbers. The pitchers with good ni-gun numbers but bad velocity had really mixed results. It does seem that velocity has the better correlation, though the high velocity guys had mostly good Ni-gun numbers (which sort of raises the question as to whether or not they had good Ni-gun numbers because they had good velocity, or could it be that the two things didn't have much to do with each other. Most of the pitchers that really struggled in the ni-gun were the softer tossers). So, we could perhaps say that we have some correlation, but as of now, we don't really have causation, and frankly, we would like to see more correlation. I will continue looking at projections from league to league using either numbers or velocity and see how the two stack up and see whether or not we can say that our hypothesis laid out previously (that velocity is a better predictor of success between leagues than numbers) is correct or even close to right with any degree of certainty.
As for Kayama himself, he falls in the below average velocity but good Ni-gun numbers camp. From a scouting perspective, the lefty is incredibly small, listed at just 5-7 143 pounds. He has a dramatic pause in his delivery where his leg just sits up the air for (according to my stop watch) about 1.36 seconds before coming over the top. I always wonder about these guys, as when they have baserunners on they have to change their delivery pretty dramatically. He apparently tucks his leg back, in a move that we see a lot in the NPB (and some in the KBO as well). Most of his pitches seem to move arm-side, but they don't come with exceptional break. Even though he is a lefty with similar velocity, I don't like Kayama as much as Kasahara.
Update: Jason Coskrey, a NPB writer for the the Japan Times, brought up a point and objection that I thought was relevant. I didn't really consider whether or not the pitchers had experience in the NPB, as some of them turned out to be veterans. This could introduce variables in the Ni-gun numbers that might mess with the data. So, I looked at the 2007 Western League, which is still a small sample size, but it gives us a little more to work with.As far as I know, these players didn't have extensive (subjective term) NPB experience before 2007. I sorted this one by Ni-gun ERA.
Ryota Katsuki: 87.16 MPH, 1.40 Ni-gun ERA, 3.76 nFIP
Kazuki Kondo: 88.26 MPH, 2.76 Ni-gun ERA, 4.20 nFIP
Shinya Nakayama: 85.43 MPH, 2.90 Ni-gun ERA, 3.78 nFIP
Kazuki Yoshimi: 88.62 MPH, 2.92 Ni-gun ERA, 3.23 nFIP
Keisuke Katto: 89.08 MPH, 3.15 Ni-gun ERA, 3.41 nFIP
Kazuya Tsutsui: 86.51 MPH, 3.38 Ni-gun ERA, 3.85 nFIP
Kenta Maeda: 87.90 MPH, 3.99 Ni-gun ERA, 3.18 nFIP
Kenta Abe: 86.54 MPH, 4.63 Ni-gun ERA, 4.14 nFIP
Takayuki Oshima: 86.43 MPH, 5.48 Ni-gun ERA, 4.31 nFIP
The average velocity of these pitchers was similar to the ones above, actually a little slower at 87.33 MPH, with no one with an average fastball over 90 MPH. The above average velocity pitchers had a 3.51 nFIP, while the below average had a 3.97 nFIP. If we use Ni-gun ERA, the bottom 4 had a 3.87 nFIP while the top 4 (leaving out the median pitcher, Keisuke Katto) while the top 4 had a 3.74 nFIP, a correlation, but not as good as the velocity. Again, small sample size, but similar results from what we have been seeing.