Beane knows what he is doing. Lawrie appears to be healthy, passed a medical. He's ~4 years younger than Donaldson, and he's entering his prime, whereas, Donaldson is in his prime. They fill their need at 3b, get very serviceable pitching prospects who could end up being quite decent. They also get a highly tooled very young SS that will hold value.
Beane has done this many times before, he's spread out his risk over several guys and saves money because he knows Donaldson is going to hit high numbers in arb. The Jays DID get the best player in the trade, right now. However, I wouldn't even call this near a fleecing because I think Barreto is the sleeper player in the deal. This happens time and time again, a team thinks they won their trade with Oak, yet 2-4 years later, you all of a sudden see the players you traded away starting to put up big numbers in Oakland and then somehow they make the playoffs.
So no, it wasn't a fleecing, unless you're a hardcore blue jays fan and love every move this team makes, then yes, it was.