That's called extortion and it's illegal. It's not an official agreement, its just talking. If the Red Sox say no, the Cubs can't make things more difficult for the Red Sox other than keep persuing Sveum, which they have every right to do. If the Red Sox say ok and still demand McNutt, the Cubs can't do anything either. But they can discuss a scenario that is mutually beneficial for each of them and keep it between themselves no official agreement. you don't need official agreements to have unethical and illegal business transactions