If they make a mental mistake you need to make them run a lap around the park, I am talking about the parent.
Each team seems a little bit different and being a new Team they might not know what you expect. Need to stop poor behavior right at the start or it will be a long season for you and maybe everyone.
Make the parents run!!!!! Love that.
Having been on both sides - a coach and a spectator parent- I say kill the beast now.
I also have noticed that many teams that have drill sergeants and correct every single little play - only turn players into robots. The players never learn to play with ball sense. What it sounds like to me...... you correct what needs to be corrected and let players develop ball sense for the rest. Good for you and the players.
Now make those parents run laps. Lol