Aoki is actually an interesting guy to compare Toritani to. There's a little under a year difference in age, and their overall Japan numbers over that time actually appear to be extremely similar, outside of the effects of Aoki's higher batting average. Now, more interestingly (and not very scientifically), the final year they both played in the Japanese League (2011 when the new balls came in), Aoki's Japan numbers were almost exactly what they've been the last two years here. Toritani suffered the same power drop Aoki (and everyone else in Japan) did, and similar the following year in the other categories. IF those numbers translate relatively well to what they would have done in the majors (and I admit that's a big if), he could be a better find that we realize.
If someone has a bit of free time, they can look a little deeper into that.