There has been a lot of criticism of Twin GM Bill Smith for the returns from trading JJ Hardy and Delmon Young. We may see some similar reactions if the Twins are able to deal some of their arbitration eligible players, like Kevin Slowey, this fall.
Of course, no one criticizes the David Ortiz trade that sent him to Boston, because there was no trade. The Twins tried to trade Ortiz and couldn't find anyone to take him. In fact, Ortiz was released only after being passed over by every major league team who could have had him for the waiver price if they were willing to offer him arbitration. Ortiz ended up signed by Boston for considerably less than he would have received if they had claimed him on waivers. But the other 29 teams clearly made a mistake, since it turned out Ortiz was well worth what he would have been paid. The point here, however, is the Twins ended up getting nothing for Ortiz.
Compare that to the JJ Hardy deal. The Twins got a couple of live arms, albeit with control issues. In addition they got rid of Brendan Harris's salary. Since, like Ortiz, the Twins had decided they weren't going to offer Hardy arbitration. This was a "something for nothing deal."
The same is true of Delmon Young. The Twins were not going to get anything for him if they non-tendered him. The decision to trade him to Detroit was another case of getting something for nothing.
Its important to remember that a players ability is only one factor in their trade value. Even when they still have value, it may not match their performance very well. When Johan Santana was traded, it wasn't "something for nothing", but it wasn't really a "Cy Young award winner" for prospects either. The Twins were only giving up Santana's last year with the team and a couple draft choices. The players they got in return had many season's ahead of them that the Twins controlled.
We may see some other deals this fall where the baseball value of the players traded doesn't seem to match. But you need to look at their value through the eyes of a GM. Sometimes trades are made to get something for nothing.