I certainly don't claim to know all the details. And really, I'm not sure that I remember all that I knew at the time!!!!
However, I have a recollection that the deal was reportedly "done" ( this is what I was hearing in the Boston media at the time ). Then seemingly overnight Horseface had a deal with the Yankees.
I remember that while the Sox were courting Horseface, the Boston media was reporting that the Yankees had no interest in him ( lol ). Then just before the Sox were about to sign Horseface, the Yankees signed Nick Swisher. I was jumping for joy at the time because I saw this as a major victory for the Sox! After all, the Sox were about to get the all world Horseface, while the Yankees had to sign Swisher.
Maybe my memory is not all that great?
In any case, the Yankees signed Horseface and he has been a monumental bust ( in MY OPINION!!! ), while Swisher proved to be a comparative steal by being productive and versatile for the Yankees for far less money. The Yankees should have kept Swisher. But hey, who the heck cares???? They made a mistake signing Horseface and compounded this mistake by letting Swisher slip away!!!!!!
Ultimately, as Bell says, it does not really matter.