I'm a former club coach, now just coach high school. We made it a point to see at least one game for every potential varsity player that we knew of this fall. For most we saw two or more. We did this because sometimes we imagine a player as one thing and their club coach sees them as something else. This caused us to turn one of our defenders in to a striker. One player that is playing two years up is a six for her club team. Great player, but not the type of six we want as she dribbles too much and we want someone to just sit in front of our back line. So she is going to float between JV and varsity because we see her as a 9 and have three others ahead of her. She wants to play varsity, but we think she will develop better by playing 80 minutes a game. Our starting right back is a forward on her low level club team, but fits our style because our cb's are slow and we are a high press team. She's super fast and physical.
I'm sure some coaches are biased, but most I've met just want to win. Our best left mid is a freshman, but has maturity issues so we have put her on the JV even though she's clearly more talented than players two years older. We have six kids who play CM on their club team but for our style of play the best one is actually a winger on club.
I could go on and I'm sure shenanigans happen, but in general every HS coach I've met is thoughtful and competitive. If your DD or DS will make an impact they will be on the field. By the way, on our roster of 19, we asked everyone what they see their role as. All but two think they should be starters who play almost the whole game. If only we could play 17 kids at once everyone would be happy.