There have been times I wanted to fire my coach too. Leading by one point with the ball and 17 seconds left, my SG jakced up a three, the other team got the rebound, scored and promoted. I sold that player, blew up my roster and sat in my division for another year.
I have since gone to strictly follow depth chart, and I have not really seen any game managing issues like the one you described. I suggest you do the same and see if you notice a change in your players minutes in the fourth quarter of games.