What Will Yu Darvish’s NPB Stats Look Like in the Major Leagues?

Introduction

Yu Darvish’s actual stats are on the very bottom of this page.

As you may know, Yu Darvish, an elite Japanese  pitcher may be coming to the major leagues next year. Teams bid on a posting fee (paid to Darvish’s Japanese team, the Nippon-Ham Fighters) for the 26 year-old and the winning team –  the Texas Rangers  – gets to negotiate a contract with him. If the negotiations are successful by the 4 PM CT deadline on January 18th, Darvish will be pitching for the Rangers next season. The obvious question is how good is he? We have been told that he is really good and his numbers (career 2.00 ERA) make him look good, but how will he perform in the major leagues against the best hitting in the world? Daisuke Matsuzaka was supposed to be good, but he has not performed as well as hoped with the Red Sox. So it all boils down to this: What pitching statistics have historically correlated well between the NPB and MLB?

Method

First, I decided to only use players who began their career in the NPB, which excludes American players like C.J. Nitkwoski and Colby Lewis. According to Japanese Ballplayers, this list comprises of 40 players, 29 of which are pitchers. Then, I found the amazing Data Warehouse at Japan Baseball Daily, where all of the NPB stats in this article originated. Finally, I gathered all of the NPB stats for each of these 30 pitchers (including Darvish) and compared them with major league statistics from Fangraphs. I excluded all statistics from players in the NPB after they appeared in the major leagues. I added Darvish’s calculated major league statistics based on the trend line for each (marked by the red data point).

Results

FIP

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Darvish MLB FIP: 4.36

NPB FIP is calculated according to the formula on the Fangraphs Glossary, excluding intentional walks, since I don’t have that data. There is basically no correlation between NPB FIP and MLB FIP.

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Home Run Rate

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Darvish ML HR/BF: 0.035

There is a slight correlation here, but I would guess that home park is a very significant factor that is not accounted for in this exercise.

BABIP

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Darvish MLB BABIP: 0.283

I added in BABIP to see if pitchers were getting hit harder in the major leagues versus NPB. I calculated it as (H – HR)/(BF –  BB – HBP – K – HR). There is only a small positive correlation.

Walk Rate

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Darvish MLB (BB+HBP)/BF: 0.103

I have heard that the Japanese strike zone is much different than the Major League strike zone. It appears that the walk rate does rise a bit on average, but there is nothing very strong here either.

Strikeout Rate

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Darvish MLB K/BF: 0.203

Strikeout rate is the first statistic to show any type of strong correlation. If you can miss bats in Japan, you can probably miss them in America too.

Strikeout to Walk Ratio

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Darvish MLB K/(BB+HBP): 2.92

Strikeout to walk plus hit by pitch ratio correlates the most strongly and is the best possible indicator of how well a Japanese pitcher will perform in the Major Leagues. According to this, Darvish will be one of the best pitchers to make the transition. Kenshin Kawakami and Koji Uehara are the lone starting pitchers ahead of him in NPB K/(BB+HBP). Uehara started a majority of his games in Japan, but he did also relieve in 29% of them, which may help his ratio a little bit.

Conclusion

If Darvish can maintain a K/(BB+HBP) ratio around 2.92 as a major league starter, this will put him around the 2011 versions of Daniel Hudson and Michael Pineda. For reference, Roy Halladay’s ratio was 5.64 and Brad Penny’s was 1.12. Darvish may not be a bonafide Ace, but he does look to be at least a solid number two starter, worth about 3.5 to 4 wins next year.

Yu Darvish Stats – Actual

Here are Yu Darvish’s NPB stats, taken from Japan Baseball Daily. I calculated all stats beginning with FIP. The ERA- stat is calculated with the help of PhantasyMike who gave me the league ERA numbers. He also did a little pitch and hit type work for Darvish that I may post later.

Here is a link to the Yu Darvish stat spreadsheet if you want to download it.

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