The Globe has a nice piece on Robert Petagine today. The key question: how do his stats translate? In the same period of time, as the article notes, Hideki Matsui slugged 170 homers and 429 RBIs while Petagine had 160 and 414. So it looks favourable. If he can hit like 80% of Matsui, the Sox would have a great bargain.
And that’s where the “if” comes in - how do we translate the stats? Personally, I feel that since Japanese ballparks have different and often smaller dimensions, how the Japanese league stats translate is quite tricky. If you’re a line drive hitter, I would guess you would still hit good hard line drives in MLB. If you hit a lot of short flies that were homers in the Japanese leagues, I’d guess you would just get a lot of fly outs. And that’s just for starters. Different pitch selections, wider foul ball territory - they all add up to making the task of figuring out how Petagine will do in spring training and (if lucky) in the majors that much harder.
Tangential Link: Baseball Guru Japanese baseball primer