Are players legally required to play for teams they're traded to? (U.S. leagues)

Just to add, so you know how little you make in the Minor Leagues… The highest-paid players in MiLB get about $2,150 a month. That’s at the top. They only get paid during the season which lasts 5 months. That means that the best-paid players make $10,750 a year. The poverty level in the United States in 2018 is $12,140 for a single person household. Again, the best players are in poverty unless they have other income. The lowest-paid players are making about half as much.

So you’re not playing MiLB unless you really love to play or are hoping to someday get into the MLB so you can live off of your salary.