Sometimes, a team has to make a move when they're in the midst of a pennant race. They make a trade to bring in an established veteran and ship off a prospect, who does a great job that season for the team before heading to free agency.
The prospect, meanwhile, has a Hall of Fame career. It's a story a good number of teams know, and those that do not at least have a similar story to tell. Some trades end up working out so badly, whether in hindsight or from the start, that they become part of a team's lore.
The following is a prospect that every team wishes they did not trade.