Hiroyuki Nakajima in Context

Because of what he does, we know a lot more about Hiroyuki Nakajima than we know about the average stranger. We don’t so much know anything about Nakajima’s personality, but we know about his performance at work. Yet because of what he does and what he’s done, we also know a lot less about Hiroyuki Nakajima than we know about the average major-league baseball player. It isn’t necessary to have profiles for every player who plays in Japan, but now that Nakajima has signed with a major-league organization, people want to know more. People want to know what Nakajima’s going to be, before Nakajima makes it evident with his performance what he’s going to be.

We know that Nakajima has signed with the Oakland A’s, for two years and $6.5 million. Nakajima was a free agent, able to sign with anyone. We know that Nakajima is 30, and right-handed, and a shortstop, and projected to be Oakland’s regular shortstop as long as he’s not terrible. We know that Nakajima has a killer bat flip. We know that my Firefox initially identified “Nakajima” as a typo and suggested “Nakedness” as an alternative. And we know Nakajima’s Japanese statistics. When attempting to evaluate a player you’ve never seen, or even a player you have seen a bunch of times, nothing’s more important than the numbers.

With Nakajima, people will form their own opinions, and they’ll listen to the word of various scouts, but they’ll also analyze the statistics, because those are the living record of Nakajima’s baseballing performance. Past performance is how you project future performance. Now, those of you who have paid attention to Japanese baseball can probably just skip the rest of this post, but when looking at Nakajima’s recent statistics, there’s something that you absolutely have to keep in mind.

Here’s a graph of the raw numbers, between 2008-2012. We’ve got batting average, on-base percentage, and isolated slugging percentage. You know, the same crap as always usual.

Batting average remains fairly stable, with some drop. On-base percentage sees some drop. Isolated slugging sees a big drop in 2011 and only a very small rebound in 2012. Here’s Nakajima’s ISO by year:

2008: .196
2009: .184
2010: .197
2011: .136
2012: .140

Immediately, that’s a red flag. Something must have happened to Nakajima’s power. But what happened to Nakajima’s power happened to everybody’s power. That’s the part that you already knew about, if you follow Japanese baseball even casually. Here’s the same graph as above, only for the Pacific League overall:

There was some power, and then, there was not any power anymore. Offense in Japan got miniaturized, and it presumably has something to do with the standardization of baseballs. That took place prior to the 2011 season. I’ll cut and paste an excerpt:

The new Mizuno ball for this season has been called the noncarrying ball, a reference to the effect of the lower-elasticity rubber that encases the cork center. Not surprisingly, pitchers like the new ball for that and other subtle changes they can use to their advantage.

“It breaks better, moves more advantageously for the pitcher,” Hisashi Iwakuma of the Tohoku Rakuten Golden Eagles, speaking in Japanese, said of the new ball.

Rather than ever looking at numbers in isolation, it’s critical to look at them in context. Here we’ll place Nakajima’s numbers in context by dividing his BA/OBP/ISO by the league BA/OBP/ISO and multiplying by 100 to create “plus” metrics. This tells a better and far more accurate story of Nakajima’s Japanese career.

That’s what stability looks like, more or less. His BA+ remained between 116 and 125. His OBP+ remained between 115 and 125. His ISO+ remained between 132 and 148. In 2008, Nakajima posted a .196 ISO, good for a 141 ISO+. In 2012, Nakajima posted a .140 ISO, good for a 147 ISO+. Accounting for context, you can understand that Nakajima hasn’t slipped at all, at least not at the plate. You can understand that he’s long been one of the better hitters in the whole country.

And interestingly enough, here’s Nakajima’s strikeout rate:

2008: 17%
2009: 18%
2010: 17%
2011: 15%
2012: 13%

The league’s strikeout rate in 2012 was 92% of what it was two years prior. Nakajima’s strikeout rate in 2012 was 80% of what it was two years prior. The evidence suggests that Nakajima has gotten better about making contact, and he hasn’t really sacrificed his walks. This guy, he’s been a productive bat. As recently as last season, and now he’s not old, and he’s getting paid a little more than Ty Wigginton money to be Oakland’s starting shortstop. You can see why the A’s think this is worth the gamble.

Evaluators seem to be less than effusive with praise of Nakajima’s defense, and many wonder whether his swing will translate to the highest competitive level. Just because we’ve placed Nakajima’s numbers in context doesn’t mean now we can translate them over easily. Japanese imports are absurd to predict. Tsuyoshi Nishioka was amazing before he sucked a lot. On the other hand, Norichika Aoki just posted a 115 wRC+ over nearly 600 trips to the plate. Aoki was a worse hitter in Japan in 2011 than Nakajima was, by a fair margin. You don’t have to do a ton to stick as a shortstop, so Nakajima has a real chance.

In terms of what they mean for major-league performance, Japanese statistics are something of a mystery. But by placing them in the proper context, we can make them at least a little less mysterious. Hiroyuki Nakajima might not work out with the A’s, he might not work out at all, but in that event, we won’t be able to glance at his Japanese numbers and see a decline we overlooked. He was terrific all along.