Actually some would say that the Jap that the Yankees bought has a better chance at success than the jap that the Sox bought. The yankee jap is a lefty, and has no history of injury. Plus he's been consistantly above average. The sox jap is brilliant, but hasn't been brilliant consistantly. And has a bit of an injury history.
Any way you look at it, still a ton of money for a couple japanese guys.
If I had to guess, the yankees probably preferred the jap that they got, but they wanted to make sure the sox had to pay obscene transfer prices for their jap.