Norichika Aoki Deserves a Starting Job

When the Milwaukee Brewers added outfielder Norichika Aoki to their roster this past offseason, I thought it was a curious move — the 30-year-old outfielder was one of Japan’s better hitters and by my anticipation deserved at least a large platoon role. Yet the Brewers intended on using him in a bench role.

In his final and worst season in the NPB, Aoki was still one of the league’s best hitters. And looking at his final five seasons in Japan’s Central League, we see he was consistently a dominant hitter in a league typically starved for offense:

Aoki’s wOBA

Year	wOBA	wOBA+	JCL wOBA
2007	.395	127	.310
2008	.400	131	.306
2009	.371	123	.301
2010	.408	129	.316
2011	.320	115	.277

All wOBA+ numbers relative to the Japanese CL.

Aoki has been getting more playing time lately, but now it’s time for him to get all of it.

Entering play on Thursday, Aoki sports a .370 wOBA and 135 wRC+ — created largely from his strong .380 OBP. He has walked at a decent rate (7.6% BB-rate) and limited his strikeouts (12.4% K-rate), but his BABIP (.364) is noticeably above league average, so we have to account for that.

In the past, when a player’s BABIP was crazy town banana pants, we just said, “Oh well, he’ll regress,” and threw the data trash-wise. Now, with the assistance of FI wOBA, we can reasonably predict what his offensive production will be given a change in BABIP.

First, though, we need to predict what his BABIP will come down to. One such tool is slash12’s xBABIP calculator, which is an excellent asset and something I use in the De-Lucker chambers, but in general, my preference is to use a player’s history when possible. And though Aoki is a rookie by MLB standards, he is still a veteran of pro ball, which brings us again to his NPB numbers:

Aoki’s BABIP

Year	BABIP	BABIP+	JCL BABIP
2007	.365	120	.304
2008	.363	119	.305
2009	.319	109	.294
2010	.382	125	.306
2011	.317	110	.287

He currently has an above average BABIP in the MLB, but he always sported an above-average BABIP in the Japanese CL too. Currently, in the MLB, he has a 124 BABIP+ while his BABIP+ over his final five seasons in Japan averaged out as 116.

If his BABIP lowered to meet his NPB numbers (which I would not expect him to match), then he would maintain a .340 BABIP. At a .340 BABIP, Aoki would sport a .334 wOBA, according to FI wOBA. At a .330 BABIP (113 BABIP+), he drops to .327 wOBA.

Here is a contingency of possibly BABIP scenarios:

And if you prefer the Plus Method of analyzing data:

So unless Aoki completely changes his batted ball profile from his days in Japan — and hey, it’s a very different run environment, so anything is possible — he should be able to muster at least above-average offense.

Moreover, Aoki has thus far shown a capacity for hitting more than a few triples — leading the Brewers outfield with 3 three-baggers despite playing the least. As such, FI wOBA — which inherently undervalues doubles and triples hitters — is perhaps offering the most pessimistic of forecasts here.

If the Brewers do indeed choose to offer Aoki consistent playing time, they could even do so without even taking playing time from the other outfielders — Corey Hart could slide to first, Ryan Braun would remain in left, and Carlos Gomez / Nyjer Morgan / Tony Plush could man center field.

So unless the Brewers think Travis Ishikawa can really maintain his production, or think any of their other thus-far underwhelming first baseman can out-WAR Aoki, then there should be little in the way of a starting — or at least 60% platooning — Aoki.