Tuesday, December 31, 2013
A Simple Statistical Translation of Masahiro Tanaka
One of the issues with trying to project Masahiro Tanaka in MLB using translations of other pitchers who have made the move from Japan to MLB is that the environments those pitchers pitched are quite varied. It’s hard to believe, but Hideo Nomo came over almost 20 years ago and since then the run environments have changed, particularly recently with the introduction of a smaller ball that more closely resembles the ball that is used by MLB. The new ball has reduced run scoring pretty significantly in 2011 and 2012.
|2008||Japan Central League||3.95|
|2009||Japan Central League||3.91|
|2010||Japan Central League||4.32|
|2011||Japan Central League||3.15|
|2012||Japan Central League||3.14|
|2013||Japan Central League||3.96|
|2008||Japan Pacific League||4.32|
|2009||Japan Pacific League||4.35|
|2010||Japan Pacific League||4.47|
|2011||Japan Pacific League||3.41|
|2012||Japan Pacific League||3.37|
|2013||Japan Pacific League||4.02|
In fact, it reduced offense enough that a livelier ball was secretly introduced in 2013.
So, when we look at the stats from Japan we want to make sure we account for the varying run environments that the pitchers pitched in. I attempted to do that by calculating the pitchers’ performance relative to their league in two statistics. RA (runs allowed per nine) and FIP (fielding-independent pitching). This should account for the run environment and the differences in leagues, but I did not delve into variations in parks. So this is how the pitchers I would use in attempting to translate Tanaka to MLB performed relative to their peers in these two metrics.
Nothing fancy here. Divide the league RA and FIP by the pitcher’s RA and FIP and multiply by 100. The higher the number, the better the pitcher was at preventing runs relative to their league. Since player talent is not static, I’m only using the last three years for each pitcher before they made the move.
By this measure, Tanaka has been the most effective starting pitcher to make the jump.
So real basically, I calculated the RA+ and FIP for every pitcher who has already made the jump to MLB in MLB. Then I just used the change for each pitcher between Japan and MLB to give us an estimate of some of the ways Tanaka’s performance would translate statistically. I only used the first three years in MLB, again assuming player talent is not static.
There’s more to projecting a player than their raw stat lines, and I’m very skeptical that Tanaka’s performance would translate in the way the average player has translated. I think the key guy in this chart is Yu Darvish. He’s the most recent pitcher to make the jump, and his numbers were the most similar to Tanaka’s. Tanaka doesn’t have the stuff that Darvish has, so I don’t think expecting to him be as good as Darvish is realistic. So if Darvish is a 133 RA+ pitcher in MLB, maybe Tanaka will be more like a 120-125 guy. In 2013 there were 24 pitchers who pitched at least 180 innings and put up an ERA+ of 120 or better and all but one were worth at least three wins above replacement level and the one who wasn’t (Ervin Santana) was worth 2.8.
A 3 win pitcher is probably worth about $20M a year nowadays. So I’d expect Tanaka to get something like 6 years and $120M from someone. If it’s the Yankees, I’d be cool with it. I’m not sure I’d go much beyond that though.
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