Every MLB team is compelled to make roster tweaks during the offseason, but there are methods to these moves.
Only particular players emerge as wintertime trade candidates, typically because their departures would facilitate acquisitions of more reputable (and expensive) individuals or clear space for future contributors with greater upside and risk.
The likelihood of the following guys changing uniforms isn't necessarily high. While the Tampa Bay Rays, for example, have an opportunity to get an epic package for David Price, you can't point to anyone on the Atlanta Braves or New York Yankees—among others—who already has one foot out the door.
These players will tempt their teams to engage in trade conversations due either to the position they play, the reputation they've established or the cash they would cost to retain.