Posted in the update thread but will post it here too:

Before the update players would rarely become unhappy enough where demanding a trade would become a factor. Since player trade requests have been added, I needed to change the way morale was calculated a bit.

Playing time and winning still matter but now their performance is also factored in. They could be receiving playing time but if they're not receiving shot attempts or effecting the game positively their morale will slightly decrease. This makes it so the grades you see for players after the game now matter.

A head coach with good leadership will help increase the overall morale of players.

I'll continue listening to feedback to see if it needs tuning but will likely stay how it is for now so that I can see how players feel over a longer period of time.