I wouldn't do that trade personally, you're right as to thinking that your team as a whole doesn't get much better after the deal. I traded away Aaron Hill just today myself. If you look at his previous numbers, he tends to hit much better in April/the beginning of the year and then cools off. Obviously, this is a very small sample size as he hasn't had that long of a career in the Bigs, but this is something to consider.
***Sorry, I missed the fact that you had Longoria, as my biggest thing about not doing that trade was giving away David Wright. Looking back over all the details I'd go ahead and do that. Even if Hill's production does tail off, I would imagine his production will end up looking around what DeRosa would have done, and the Indians are only getting worse. Soriano would be a big boost too, and I like Gallardo over Doug Davis. If you feel that Longoria will continue on the pace he's at and are comfortable with parting with Wright, I'd go ahead and do this. However, keep in mind that Soriano's production is going to be severely limited in the short-term considering that Derrek Lee is still being bothered by that neck injury, A-Ram is on the DL, and Milton Bradley is just flat out horrible.
Albert Pujols is to baseball what Jesus is to religion. He's better at this than I've ever been at anything in my life. He's better at this than you'll ever be, at anything. Pujols has a gift.