Maybe have a something on depth chart that we could lock players so no others can be added to the depth chart during the game, then maybe it can over ride the stamina and just rotate the players thats on the positional depth chart regardless if they are tired or not.
I also dont know if others do it but I find it much better to set a higher stamina level and keep all starters off ST.
I play in all the leagues and I have only had one player that I have noticed play out of position and that was a WR playing DB. I didnt check exactly what position he played but was guessing it might have been a safety spot because I only had 2 on the depth chart at that time.
Unless there is and injury I barely ever get to my 3rd string HB
Just a helpful suggestion