No. 4: Gio González, Fautino De Los Santos and Ryan Sweeney to the Oakland Athletics for Nick Swisher - January 2008
González and De Los Santos were traded away from the White Sox before appearing in a single game for the big league squad. Of course, De Los Santos never amounted to much for the A's, but González went on to become a star-level pitcher for Oakland.
Just two years after the trade, he won 15 games for Oakland. The following year, he won 16. The year after that? He won 21 games and finished third in the Cy Young race. Even after he moved on to the Washington Nationals for a seven-year stretch, he was still one of the more durable and successful lefties in the league.
Sweeney, the lone member heading out the door that had already made his big league debut, had promise, but couldn't deliver on it over the course of his nine-year career. The loss of him and De Los Santos never hurt much, but González would've looked great atop the White Sox rotation over the years.
Swisher, already covered in another part of this piece, stuck around in Chicago for just a single season. He hit 24 home runs but had an OPS+ of just 93 in 2008 before being traded once again to the Yankees. The White Sox effectively turned Gio González into two awful pitchers and an awful utilityman. This deal is nothing but pain.