How so? I've seen a lot of players upset in my test runs but it seems like you can always re-sign them anyway. At this point, I think morale is more cosmetic than anything and something you can probably just ignore at least when it comes to retaining players.
I'm not sure about how it effects teams on the court if the teams chemistry is low due to all of the upset players. Although, I guess it would be balanced across the league because the bench players even on good teams had low morale from what I saw.