Like the 1997 White Sox, who were 3.5 games out of first and then decided to deal 3 of the pitchers to the Giants. In return for Roberto Hernandez (closer), Wilson Alvarez and Danny Darwin, the Giants received a handful of prospects, the only two of whom that turned into anything of consequence were Keith Foulke and Bob Howry, both of whom would later pitch for the Red Sox. The White Sox finished 1997 under .500, but made the post-season 3 years later, only to be swept by the Mariners in the ALDS, thus accomplishing the rare feat of losing a post-season series to Seattle.
So yeah, that would be bad...