In response to notin's comment:
The problem lies in the Dbacks wanting very little part of Ellsbury, especially since they are alrady trying to sell off some outfield talent.
Upton would be an outstanding addition in Boston, but it is very doubtful Ellsbury is part of the deal that gets him, thrid team or not. He simply isn't going to even be worth moving in a buyer's market for CF.
Arizona is going to want a SS at some point, and reportedly looking for a veteran SP. The latter part seems odd, because they currently have Kennedy and Hudson in front of their score of rookie talent. But if they want to keep Bauer and Skaggs IP down this year, it does make sense.
The Sox really do not have a SS to move for Upton, and that is the problem. Mike Aviles is a utility infielder, and certainly the Dbacks have hgher aspirations. They already have John McDonald and Willie Bloomquist in that role, and are unlikely to want a third. Iglesias might tempt them, but also is not going to be wothy of star-caliber in a trade.
That means, to get Upton, the Sox might need to part with a veteran SP, and presumably one not named Lackey. The DBacks might be interested in Lester. Lester's down year was really all at Fenway, where the DBacks play very few games.
However, if I had to predict anything, I would guess Upton goes to Texas for Elvis Andrus and Derek Holland. There may be anther name otw involved from either side...
Dbacks just got cliff pennington, so ss is no longer a need. A package for upton would likely start with brentz, doubront, and then a few more spects.