1
Another thing you have to consider is that most times you're getting these guys in their 30s. In most cases, they are in their decline phases and you're not getting that 1.000 OPS NPB guy.
When guys like Iguchi and Johjima went back to the NPB, they started OPSing in the mid-800s.
Also, the level of hitting in general seems to have signficantly declined in recent years in the NPB. There are a few tremendous pitchers, but there is not a single guy I'd be confident in as a plus hitter in the MLB. The late 90s, early 2000s seem to be the peak for NPB hitting talent.
Not only are there no more Ichiro, H.Matsuis, and Ogasawara monster type hitters, but there are no Johjima, Iguchi, Iwamura type hitters anymore either.