How do we know Simpson didn't take on board his suggestions and implement them? Assistance coaches are hired to assist, the suggestion they don't have any influence on the coach would not be correct in most instances.
I didn't say he didn't I am just saying that Assistant coaches don't have final say. Never have and never will.
The coaching group generally will work together to implement the senior coaches plan. But ultimately the senior coach has final say on everything.
Maybe he did do everything the assistants said? we will never know this.