In the penny-pinching world that is the multi-billion dollar baseball industry, there’s nothing more valuable than this: a star coming into his own who’s still making the league-minimum salary. 25 of those players on a roster is a profit-maximizer, and if the free agency freeze-out we saw over the last two winters is any indication, maximizing a team’s bottom line is almost equally as important as winning games to many of the ownership groups out there.
From a pure baseball perspective, finding teams that might be willing to trade such a player is the hard part. Usually, the only teams willing to listen - especially mid-season - are the ones who are a) in a rebuild and b) out of contention for the current season.