Why would you trade cost controlled assets and take on Fielder's contract, when we could have just taken on his contract for nothing a couple years ago?
Since they paid $30 million of the contract, it's not quite the same thing. Instead of a 9/$214 million contract, you're essentially giving him a 7/$138 million contract. I'm not saying that's worth it, but it's not the same deal.
I don't mind that at all for Fielder. Since scouting reports don't accuse him of losing his bat speed, I just chalk his year up to the fact that he was going to unnamed personal problems in Detroit and that he's streakier than you think. This is now the third such "drop-off year" that he's had in 7 years. The other 4 years he averaged 5.1 WAR. If you just start him at 4.5 WAR and assume the regular .5 win decrease per season, that's something like 21 wins over the next 7 years, which in this market is about $130 million.
Considering the potential for a 4-win upgrade at 1B - especially with the fact that it's the kind of big bopper, hitting, OBP-heavy upgrade we need most - I wouldn't shy away from that deal.