With the Japanese Minor League (the Ni-Gun or 2-Gun of the NPB) season over,, I wanted to look at the statistical leaders of the league through some relatively simple metrics. In this post, I'll take a look at the pitchers (soon I'll take a look at the hitters). I won't use minimum age or inning requirements, posting all of the numbers below, but afterwards I will have some notes on young pitchers that might be worth watching.
First, we need to look at the league averages of the numbers we are looking at, all pretty simple percentages. While I won't calculate kwERA for all the pitchers, Ni-Gun league average in 2013 (I didn't separate Western or Eastern League) was 4.48. Instead of using RA9 or ERA (though I kept the ERAs of each pitcher in the spreadsheet) I based everything off of percentages from batters faced. For instance, 11.19 % of batters scored a run, while 9.4 % of batters scored an earned run in the Ni-Gun in 2013. 23.3 % of PAs ended in a hit (instead of using traditional batting average I used hit percentage of plate appearances), while 8.3 % ended in a walk, 15.83 % strikeout, and 1.58 % homers.
It might be helpful to compare the Ni-Gun run environment to the environment of Major League Baseball (in 2013). There are slightly more runs scored in the MLB (11.96 % of plate appearances), with more of them being earned (11.13%). There is a considerable higher amount of homers (2.75 %) and strikeouts (18.13 %), but less walks (7.35 %). There are also more hits allowed in the Majors as well (24.15%).
So here are all the numbers of all pitchers who who threw in the 2013 Ni-Gun season. The raw numbers are taken from NPB's official English site, with my percentages added to them. It is sorted by runs scored percentage.
Out of pitchers with at least 200 batters faced, Marines veteran and playoff starter (though 2013 turned out to be a real breakout year for him) Takuya Furuya had the best run percentage. Baystars' lefty Kenji Tsuchiya probably qualifies as the best run percentage by a prospect. He has pitched an insignificant amount of Ichi-Gun innings, but as you would expect, he was better than average across the board in every category in the Ni-Gun this year. He throws a change and a slider, both under 80 MPH, with his mid to high 80 MPH fastball.
The leader in strikeout percentage with at least 100 batters faced was Ryuji Ichioka, a 22 year old right-hander for the Yomiuri Giants. He has thrown a handful of innings for the Ichi-gun team for the past two years, enough that we know (via NPB Tracker data), that he has a fastball just short of 90 MPH, with a slow curve, a mid-70s slider, and a low 80s forkball. His walk and home run rates were below Ni-Gun averages as well. Just below him, with more batters faced, and a lower hit percentage (though higher walk and home run rates), is Mizuki Tsuchida, a 23 year old with the Giants who hasn't pitched in the Ichi-Gun. Tsuchida is a former Island League (independent ball) pitcher who can get up to 92 MPH with a slider as the main secondary weapon.
The best pitcher (100 PAs minimum) at limiting hits in the Ni-Gun was Mu-Young Kim, a 27 year old with the Softbank Hawks. He has gotten 31 innings with the Ichi-Gun team over the last two years, and has been effective, with a 3.93 kwERA. His fastball has averaged about 88 MPH in the NPB. The Fighters rookie Hidekazu Kawano was one of the most effective at limiting hits as well, with a high K rate but high walk rate in the Ni-Gun before being effective in the Ichi-Gun.
The best guy at avoiding walks was Hirofumi Yamanaka, a 28 year old Hawks pitcher that made his Ni-Gun debut in 2013 (unsuccessfully). In the Ni-Gun, he had an above average strikeout and run rates, and gave up as many homers as he walked batters. As you might expect, most of the low walk pitchers are older pitchers, not really prospects. The lowest walk rate out of pitchers 24 or younger was the Giants' Ryosuke Miyaguni, a 21 year old right-hander with over 180 innings of Ichi-Gun experience. There his walk rate hasn't translated, almost doubling to 8 %, though he has decent numbers in the NPB. He throws only about 87 MPH with a lot of sliders.