The Post-Gazette has a blog entry about the Salomon Torres trade today. That trade, which brought pitchers Marino Salas and Kevin Roberts to the organization, looks like a bad one now, but I'm not sure what we can learn from it.
As I've said before, trades should be judged based on the information available when they were made. At the time of the trade, Torres was a 35-year-old reliever with injury and conditioning issues who'd posted a 5.47 ERA in 2007. His peripherals that year indicated his ERA should have been slightly better, but it was still an awful season, and when a 35-year-old reliever has an awful season, he's usually done. Torres himself seemed to think that might be a possibility--he considered retiring rather than reporting to the Brewers. A 67-win team needs a pitcher like the one Torres was after 2007 like a fish needs a bicycle.
So the Pirates swapped him for two live arms in Salas and Roberts. While minor league relievers usually aren't worth getting excited about, the Pirates needed pitching depth badly at the time, and they weren't giving up much. Salas and Roberts didn't work out--Salas pitched well in the minors but flopped for the Pirates, and Roberts stunk at Class AA Altoona, although he pitched better at Class A+ Lynchburg. At the time of the trade, the chances that either Salas or Roberts would contribute much in the big leagues were small, but those chances are still often worth taking, because if a reliever can come through the minors and be a valuable contributor in the bigs, he can be controlled very cheaply for several years.
I didn't like the trade at the time, because I didn't feel that the Pirates got quite enough back. But shipping Torres off for young players was the right idea, and it was a reasonable trade that might well have paid dividends.