It seems while I was asleep last night the Reds, Indians and Diamondbacks traded a total of 9 players, with each seemingly filling a whole that each organization had. I'll do this by team.
Reds: They did well, trading Drew Stubbs and Didi Gregorious (to Cleveland and Arizona, respectively) and getting back Shin-Soo Choo, Jason Donald and $3.5 million. They plug an offensive whole in CF with Choo, and he'll leave after next year anyways when his contract expires, not getting in the way of Billy Hamilton (who I think will be ready in 2014).
Indians: Retooling and trading vets for prospects is good when the returns are this good. They get Trevor Bauer, who should be a fixture for some time in their rotation, Drew Stubbs who, while he had a bad year last year certainly could bounce back, and two relievers in Matt Albers and Bryan Shaw. he Indians will miss Choo, but he's a vet who's contract runs out next year, and they ain't going anywhere.
Diamondbacks: I'm still perplexed on this side of the equation. The Diamondbacks get Didi from the Reds, but send their top pitching prospect out to Cleveland, and also get throw-ins Tony Sipp and Lars Anderson. I guess they had soured on Bauer, who is something of a free spirit, but this feels like selling pennies on the dollar; if you don't like a player, but other teams do, sell him to them like you still like him.