Your HC coaching style just gives you additional plays for his style that the other coaches don't have. The game planning is the same as if you hit "recommend" for everything - the AI takes your roster vs their roster into account as well as your own play success to choose which plays to use, but there is minimal difference to the underlying gameplanning code. This will hopefully change in the future, but it is a lower priority to a few other things; so yeah, at this point I don't know that you should spend a ton of time worrying about your HC coaching style in a roster-only league.