Check the decline on Ryan Howard (already 29 and with old man skills):
Career v. Lefties
Yes, I've left out RBIs (149, 136, 146) and HRs (58, 47, 48). The point is simply that you couldn't trade for him, plug him in for years, and win the deal.
The pitcher isn't much of a loss even though I dislike Gallaraga and think the Jays' pitcher is a huge risk: Zambrano's going to break down, and on the surface, you do upgrade your hitter a lot.
I was about to say I wouldn't do it, but I'm convinced you could trade for him now, enjoy him for a year, and resell him next offseason (or if you fall out of the race unfortunately this year). You could sell him higher than this, I'd think. viewtopic.php?t=371093