Back in December, the Milwaukee Brewers coughed up $2.5M for the negotiation rights to Japanese outfielder Norichika Aoki. Aoki, who was set to turn 30 in January, had been dubbed by Patrick Newman of Fangraphs "the best pure hitter Japan has produced since Ichiro" not too long ago, but after a disappointing 2011 campaign with the Yakult Swallows that saw him hit .292/.358/.360, his stock had dropped. For reference, the $2.5M posting fee was essentially half what the Minnesota Twins had paid for Tsuyoshi Nishioka's negotation rights in the previous offseason.
The Brewers ending up working out a pretty cheap deal for Aoki, giving him an incentivized two-year contract worth $2.5M in guaranteed money, plus a team option for 2014 valued at $1.5M. Specifically, they'd pay him $1M in 2012, $1.25M in 2013, and either buy out his option year ($250K) or exercise it and pay him the $1.5M. If Aoki reached all his incentives, he'd have the potential to earn a maximum of $8.6M.
The plan was to use Aoki in a bench role, as a fourth outfielder -- which made sense, given his useful skill-set: a left-handed bat that could provide speed and fill in at any of the three outfield positions.
But Aoki made a seamless transition to the majors, and by late May, he was boasting an OPS in the mid-800s. With Corey Hart sliding over to first base, Aoki earned an everyday job in right field. As of today, his season line sits at .281/.350/.403, which in addition to his 18 steals, has made him a solidly above average hitter (.334 wOBA, 109 wRC+). He hasn't hit for much power (.123 ISO), which is typically concerning for a corner outfield bat, but he's made up for it by putting the ball in play with great consistency (9.9% strikeout rate). And while his walk rate is slightly below average, he's also reached base ten times via the hit-by-pitch. (In fact, if you treat HBPs like walks, no qualified hitter gets a bigger boost from BB% to BB+HBP% than Aoki). Oh yeah, and he also happens to have one of the lowest GIDP rates in baseball, having only grounded into two double plays this season.
And now we come to another important matter: defense. Aoki has spent most of his time (577 of 765 innings) in right field, where he grades out as neutral by UZR, and +3 runs above average by DRS. Overall, UZR has him at around -4, DRS has him at +1, and FRAA has him at +0.5 this season. But as we know, defensive metrics, particularly in small sample sizes, should be taken with a grain of salt. I haven't had the opportunity to watch much of Aoki's outfield play, but Jaymes Langrehr (@JaymesL) of Disciples of Uecker was kind enough to give me his extended thoughts on Aoki's glove:
Nori's metrics paint him as a solid-but-unspectacular RF, and I'd say the eye test would generally agree with that. His arm would be considered below-average for a CF, so it's less than ideal for a RF. He's also not exceptionally fast, but I'd describe him as a smart defender. He seldom takes a bad route, and while he's misjudged some flyballs this year, I'd be willing to write that off as him playing a position he's not entirely used to (he was a CF in Japan). He's always seemed to get good jumps on flyballs, too, which helps make up for average speed. He's certainly less adventurous than most of the outfielders on the Brewers roster.
Looking through the various implementations of WAR/WARP, the consensus estimate of Aoki's value this season is around one and a half wins. Considering that Milwaukee only paid $2.5M for the negotiation rights, and that they've only paid Aoki $1M this season on top of that, it's safe to say that they've already gotten their money's worth. Additionally, they have him under contract at one million and change for the 2013 season, as well as the 2014 season (if they decide that it's worth keeping him around for another year at that point).
Milwaukee took a gamble on Aoki this offseason, but they've been rewarded for it, as his production has quietly translated well to the majors.