Maybe this is widely known re: player morale

[tessl]

I may be the last person to figure this out but yesterday during a game I paused the game and looked at attributes of my relievers and noticed they were significantly different in some cases from the attributes of the same players on the manage roster screen.

If you want to see the impact player morale is having on attributes that's a way to check it. I reshuffled my bullpen and sent a guy to the minors because of it.