I know there are already a zillion of these on Iwamura, but I quite frankly don't want this to get lost as a comment in one of the others. ;-)
I was perusing Aki's Fangraphs page this morning and noticed a few things about him:
1) His line drive percentages the previous three seasons ('07, '08, '09): 20.2%, 19.9%, 20.7%. This season: 13.3% Groundballs the previous three: 46.2%, 46.6%, 43.6%. This season: 55.1%. This confirms what a lot of peoples' eyes have been reporting: he's pounding a lot of balls into the ground.
2) His other rates are mostly the same: his BB% and K% haven't changed particularly significantly (actually his BB% has increased slightly). His isolated power is down somewhat.
3) His first-pitch strike percentage is way up. The previous three years were 55.3%, 53.9%, and 52.7%. This year, he's in an 0-1 hole 62.7% of the time. I suppose that might mean pitchers are then getting to their out pitches sooner and more frequently against him, and because out pitches are often breaking balls, he's pounding them into the ground (see #1).
4) The percentage of pitches he sees that are fastballs has decreased. The past three years: 59.1%, 65.3%, 67.9%. This year: 61.7%. He's also seeing more sliders and curveballs than he has in any previous season.
5) His out-of-strike-zone swings and swinging-strikes are not particularly out of whack for him. 17.2%, 18.2%, 14.5% the previous three on the former against 18.1% this season, and on swinging strikes 10.4%, 7.1%, 8.3% the previous three against 8.6% this season. His contact rates are similarly the same.
Putting all of that together, it would seem to me that Aki is taking an increased amount of first-pitch strikes this season, and is getting set up for more breaking balls that he is then pounding into the ground at a somewhat higher rate than expected.
I don't think there's any particular "skill" to taking first-pitch strikes that Aki could have lost (especially since he's taking more first-pitch strikes, yet increasing his walk rate), he's just been unlucky and seen a whole lot of them. Because he's in pitchers' counts more often, he sees more breaking pitches, which can result in more groundballs. And then if he gets a little unlucky with his groundballs on top of that, you've got a minor disaster on your hands.