Talent evaluators from [the Padres and Diamondbacks] have scouted Pittsburgh’s minor-league affiliates in recent days, as the teams prepare preference lists of prospects they want in the potential deals.
Upton is in the midst of a disappointing season, but he's still a superstar-caliber talent, he's a year younger than Andrew McCutchen, and he's signed through 2015, so the Pirates would have to give up a ton to get him. The thing is, though, he might well be worth it. He's a building block, and an important one.
Two Pirates pitching prospects — right-handers Gerrit Cole and Jameson Taillon — were selected for Sunday’s All-Star Futures Game in Kansas City. The Pirates are said to be more reluctant to trade Cole than Taillon, in part because Cole is closer to the majors.
My guess is that a deal for Upton would start with one of those two guys and include a couple other big prospects as well. This would be such a blockbuster that it's hard to imagine it happening, but it's certainly fun to dream of an Upton-McCutchen-Marte outfield (if Marte weren't in the deal himself, that is).