And doesn't involve the Reds.

Rockies trade Troy Tulowitzki to Diamondbacks for Justin Upton and Tyler Skaggs.

Rockies are desperate for pitching and could trade their best player in order to get it.

Diamondbacks are desperate for a SS and will likely trade their best player to get one. They also have young pitching in spades (Skaggs, Bauer, Bradley, etc.)

That would give Colorado one HELL of an OF with Upton, Fowler, and CarGo.

Just my own speculation, no merit to it beyond that. If it happens, it would rival the Dodgers-Red Sox and Tigers-Marlins blockbusters of the past couple years.