Much has been said about the Josh Donaldson trade, so I'm going to keep this short and sweet.
This team probably wouldn't have been in the mix with or without him. Having an All-Star and MVP candidate at third base would've been cool, but our starting rotation would've been pretty barren without Graveman and Nolin. Perhaps we do somewhat well with Gray, Kazmir, Hahn, Bassitt and Chavez. But past that, there would be minimal depth. We'd basically be relying on Pomeranz, Brad Mills and Zito. Both Brooks and Doubront weren't even in the picture, and neither of them are that good. Brooks is most likely a AAAA guy, and I don't think Doubront fits into our plans past this season.
The point is, Josh Donaldson wouldn't have made this team a winner. We didn't even begin to dissect the bullpen. Anyway, what benefit would holding on to him for another year have had? To trade him this coming offseason, off another excellent year, would have netted perhaps an even better return for someone who's shown that 2013 and 2014 weren't just a flash in the pan. Perhaps that would've netted a better return than Lawrie, Nolin, Barreto and Graveman.
That being said, who knows what happens if we don't move Donaldson after 2014? We most likely don't move Robertson without acquiring Barreto, which means that we don't get Zobrist and then flip him for Sean Manaea and Aaron Brooks. There's also a good chance Danny Valencia isn't with the team (if he is, he's either at second base or left field). This move was also made before Yairo Munoz had a breakout year, so there was more of a need for Barreto.
In reality, it's all a moot point. There's really no way to figure out what would've happened. It seems likely that we could've gotten an even bigger return solely for Donaldson, but what about those other pieces? What would the organization look like as a whole?