Since everyone has access to TeamViewer, we can now see which players on our teams are "unhappy" due to not getting enough playing time and who have demanded trades. This is the game's natural defense mechanism against sitting quality players (i.e., its anti-tank mechanism) but as far as I can tell, it doesn't keep you from playing a guy. Let's fix that.
Caveat: It's possible for a player to become "unhappy" and demand a trade AFTER the trade deadline. This is dumb because there's nothing you can do about it. Keeping this caveat in mind, I propose the following:
1. If a player starts the season "unhappy" he must be deactivated until traded.
2. If the player becomes "unhappy" during the season but before Sim 8 (when the trade deadline occurs) may be played up until the trade deadline, but may not be activated after the trade deadline.
3. A player who becomes "unhappy" during or after Sim 8 (when we can't do anything about it) may be played as normal through the end of the season.
Basically, once a guy goes Jimmy Butler on you, you have to start finding a way to trade him or he'll refuse to play.