This one came up a couple of times in the comments. It’s interesting because it’s an example of how, even when Dave Littlefield did something right, it wasn’t by design.
On July 22, 2003 — the day before they traded Aramis Ramirez — the Pirates traded lefties Scott Sauerbeck and Mike Gonzalez to Boston for right-handed relievers Brandon Lyon and Anastacio Martinez. Boston was in a pennant race and wanted a left-handed reliever, and Sauerbeck was an overrated lefty specialist who’d had one really good year in 2002.
Judged at the time, the trade was a poor one for the Pirates because of the inclusion of Gonzalez.