Try using Strictly Follow Depth Chart instead of Let Coach Decide. The coach will replace your starter if he decides that one of his substitutes is better fit for the position.
But to the point of not even starting the players that I choose? Isn't that a little extreme? What's the point of making a line-up with "let coach decide" then? If it is like you say, then it would be the same as just dressing up 12 ppl and not making a lineup at all, then the coach would pick whatever he wants, but I don't think it's that extreme, or is it?
That's why you have the intermediate option, Coach Picks from Depth Chart, which is somewhere in between the two.
"I don't know half of you half as well as I should like; and I like less than half of you half as well as you deserve."